In your opinion, is scrum a waste of time? Why?

Sometimes or usually. I haven't decided on which yet

That probably depends on the organization and the scrum master.

Correctly done it should be short efficient meetings that help remove blockers while at the same time provide any status updated that stakeholders need.

Used wrongly it can be as bad as anything.

A hammer is a good tool to use on nails, its less good when used on screws even if it does work but its very bad if used on softer heads.

In general I would say I still like it. It's heavily dependent on the product owner in my experience. If the PO is a classical product manager it's really hard to have any benefits with scrum. Same goes with the scrum master. If he does his job right meetings will get more effective and teamwork between the devs will get a lot better. If not you have just one more person that's working as air heater.

I don't think so, but it can be if implemented poorly. I worked in projects where it was all just about the numbers and graphs and it was completely pointless for us to listen to some manager explain burncharts to us every retro and why we are all not doing good enough.

On the other hand I also worked (and currently working) with a team that has scrum implemented decently and it promotes a lot of communication among the team and retros feel actually good with actions points often being implemented with some time.

I don't mind them at all and in-fact when I started at the company, it wasn't as well implemented, but with the help from another colleague that started almost at the same time with me, we pushed for optimizations and managed to get it to a good place together with both the old and new manager that replaced her few months later. Feels good when things work