It sounds like you had a really good advisor. My limited world view saw that nearly all grad students had to work on the projects that their PI got funding for

It sounds like you had a really good advisor. My limited world view saw that nearly all grad students had to work on the projects that their PI got funding for. Their own research was never financially possible unless they got significant funding from outside their lab. Even my SO, who got grad school fully paid for by a smaller government agency, couldn't work on individual research and had to do what the PI said.