I've worked for both startups and corporations. Corporate jobs are soul-crushing because everything about the environment seems to hinder you from producing real value and from learning new useful things. Corporate jobs hurt your inner creator and they destroy your sense of pragmatism.

Most of the stuff you learn in corporations are anti-patterns that you have to unlearn after you leave.

The reason why corporate jobs feel so meaningless is because most tech corporations have had a long term monopoly over their respective markets. They haven't had to really struggle on the market for several decades in some cases... Inside a corporation, mediocrity is the definition of success. If employees can produce something mediocre that only just works, it will translate into disproportionate revenue gains due to centralizing and monopolistic market forces. I think that this is what is meant when people talk about the "golden cage".

That's why I try to avoid corporate jobs. They pay well and you do learn some stuff in the first few months but after that your skills start degenerating and a lot of people don't notice it when it happens to them; then they get stuck in that job (or other corporate jobs) because no efficient company exposed to normal market forces will hire them.

Also note that the definition of 'normal market forces' is relative. Most startups which don't go through the normal corporation-controlled VC funnel (e.g. bootstraped startups) have a really tough time working against centralizing and monopolizing market forces.