Good advice here. I too would be out riding my motorcycle or skiing all day if I could get paid doing it. Like you said not always the case. And the term starving artist really does apply.This is a worthy sentiment, but not entirely realistic.
I'm a graphic designer and I do not wholly love what I do. But at the time I got in to it, I was looking to do something that involved computers and got me out of having to work physical jobs.
I love design well enough and have enough skill to remain employed and keep food on my table. But, if I did what I thoroughly enjoy, I'd be playing Dungeons & Dragons (or other RPGs) all day and be homeless.
My son, who is 19, is currently in his second year at ASU. Towards the end of the first year he was stressed and agonizing because what he'd chosen as his major turned out not to be thoroughly enjoyable to him. I told him that I'd always seen him as doing something in IT because he's always been involved with computers.
My best advice to him was to find something that he liked well enough to still be doing in 30+ years. Something that he wouldn't regret wasting his life on doing.
I doubt IT is thoroughly enjoyable to him, but he's much more relaxed and interested in what he's doing now.
To add what you have mentioned, turning a hobby into a living isn't always the best idea either becuase what you enjoyed could end up being a grind and kill off anything you might of enjoyed in the first place. Who knows until you try.