I often hear
You will be promoted as lead if you act like it or take charge

That is really stupid, there is difference between responsibly and effort.

Why would i put effort for things that i am not getting paid for ?
Fuck that

Because if you do, you can get a promotion and make more money over your lifetime then if you don't.

"We need you to prove to us that you're capable of doing the job"

Well then I need you to prove to me you're capable of paying me for doing that job. Let's just start proving this to each other at the same time.

the company ain't gonna put the effort to train or tell you want they want either, you have to mind read them and give them want they want

fuck this world

Yeah I have been told the same after someone resigned. I promised 3-4 months of good tech lead work in exchange for a promotion as official tech lead. I was previously a dev in the team for 2 years and a half.

I kept my word at the end of the bargain beyond expectations, they did fuck all. People were scared at first when I took over because I had to walk in the footsteps of previous tech leads who gave their resignation and we were a core team. We all shared the management workload beforehand.

Management gave me excuses like "you are too young to lead" or "if I hire a senior he will put you aside and take the lead instead" to not promote me. Yeah right, pure gaslighting. They wanted me to take bullshit management courses to prove I had the knowledge. In reality, some people were uncomfortable that I was the only 26 year old tech lead.

Then, I promptly gave my resignations and they started panicking on how much money they would loose and finding replacement lol.

Sometimes promotions come by switching jobs

I had that with becoming a senior. My manager wanted to put me forward for a promotion but there was a pay/promotion freeze on and we only do reviews every 6 months. I had to act like the role that I wanted for almost 3 cycles and then got an early promotion because we were hiring at the same time and I'd be the manager for the new person. My salary was also increased by double what it would have been because the new person that I'd be managing would have earned more than me.