Take the worst possible estimate you can come up with. Multiply by 3.

Usually ends up pretty close in my case at least.

As a teacher myself, I will always advice young people to go to school. Though I imagine it differs on the quality of education in your country.

I live in the Netherlands and here it's quite good overall. It's no Ivy League and there are plenty of exceptions but overall any technical study here is a good study.

I also teach at a small school (220 software engineering students) so I actually know my students and what generally need to get ahead.

But my main reasons for actually doing a study instead of going the self-taught route:

1. You spend +/- 4 years in presence of peers that are more or less in the same life phase as you are. You will make friends for life.
2. Companies value a diploma. Good for you that you landed a job on your 19th. Just wait until your 25, wanna switch jobs and don't even get to the second round of any application process because your CV does not list a diploma. This might change in the future but not for the next 5-10 years.
3. You will learn foundational stuff about most thing IT-related. Some things you'll never use. Some thing you'll use unknowingly every single day
4. It teaches discipline without major impact on your life if you fail something. OK, you failed a course. So what? Take it next year and take the time to do a side-project or internship during your study delays. It will teach you some life lessons without it costing you a job or your life savings, and you get some extra time to learn as well!
5. Retirement age by the time you retire will be 75. There's plenty of time to work. Why not spend 4 years with peers in a relatively safe and fun environment first?

TL;DR - small schools are actually fun, attend one

Become a farmer within a tight-knit community of some 100 people. Have a couple of cows, chickens, sheep, crops, fruit trees, ... Everybody takes care of each other and we're (mostly) self-sufficient.
Preferably with some good hiking areas and nice vistas nearby.

Taught myself how to program a Texas Instruments 84 graphical calculator to solve the common mathematical equations in high school. Shamelessly copied a lot from the internet but learned quite quickly. Things like solving 2 and 3 degree polynomials, prime factorization or calculating integrals and stuff.
I quite liked how I could make life easier for myself and eventually class mates. Just rolled into software engineering afterwards I guess. No regrets thus far...

Practice, practice, practice. Was 20 when I learned programming in uni. I found it so hard. But I created the time to do all the homework and did as many stupidly difficult side projects as I could of. I probably never finished one since I could barely nest an if-statement in a loop, so forget that homebuilt pension calculator.
But... I learned so much by failing all those projects. Still try to do as much stupid stuff as I have time for and I heartily recommend every programmer to do the same.
Start 100 projects, maybe 10 of them are viable. And of those 10 only 1 will work. But you'll learn the most from the other 99.

My coach during my first internship. The first 4 weeks he took the time to pair program at least 3 hours a day with me. He needed the time for his own work but still invested in me. His technical prowess was insane. His code was so easy to read that it took me less than 3 weeks to get to know the 500,000+ lines codebase. He could explain the most complex stuff at such a fundamental level. After those 4 weeks of coaching I wasn't an intern anymore. I was an actual member of the team. Also learned a lot of useful non-technical skills like planning and communication from him.
Then after those 4 weeks he resigned and started working for another company. At the time I found it a dick move. It took me months to realize he managed to get an intern with 0 experience so comfortable around a code base that everybody treated me as a worthy colleague and engineer. It was a matter of days before people would ask me hard questions and I found I could answer each and everyone of them.

Pure sensei this guy was. Such a different level of knowledge and ability. I hope to become such a model for all of my students.

Not seeing my students while I teach and coach them. I've lost quite a couple of them due me not being able to literally sit next to them and talk with them. Online lessons are okay bit it's the physically being there that makes me get those students back on track. Now I can not reach them. Ugh.

Getting the company to sit me down next to one of their teams for a couple of hours. Just see what they're doing. How work is managed, how code reviews are being done.
You want to hire me, not the other way around. But good luck in explaining this when you have to write a doubly linked list in pure C because some guy on a conference said that every dev needs to be able to do that.

It was called a hackathon, but was probably more a CTF on a distributed TOR network. Organized by Dutch tax police (FIOD) for students. Finished it single-handledly in 18 hours, in front of several teams consisting of 6 people. Immediately got a job offer, but declined since I still wanted to do a master's :)

Basically an IMDb clone that reads my IMDb watchlist. I can add counts to it though (i.e. I watched a movie 10 times). Every day it runs runs the changes of that day through the OMDb API and then shows the amount of time I could've spent not watching movies on a dashboard.

Currently I've spent almost 10% of my life watching movies and series. Dear lord. Why did I make this.

In PHP, strings are classes, functions, whatever you them to be. I feel so filthy, I need a shower after typing this.