I agree with the first half of your reply and the overall sentiment that freeriding like this is just gonna leave you just further disappointed and dissatisfied in your life.
However, one thing i disagree with you and a lot of other similar replies on is that finding another more challenging job is the only way to solve it. Wouldn’t OP working on a side project or contributing to open source with all that free time he has solve the existential problems he is having just as well? Not even mentioning the fact that doing so sharpens his technical skills, adds projects to his resume, with the main difference (as opposed to working an intense job) being that he has way more freedom to choose what he wants to work on and how.
However, one thing i disagree with you and a lot of other similar replies on is that finding another more challenging job is the only way to solve it. Wouldn’t OP working on a side project or contributing to open source with all that free time he has solve the existential problems he is having just as well? Not even mentioning the fact that doing so sharpens his technical skills, adds projects to his resume, with the main difference (as opposed to working an intense job) being that he has way more freedom to choose what he wants to work on and how.