As with everything in life it comes down to compromises.
If your willing to compromise say financial security to chase some whimsical theory of a dream then good on them.
Others are not willing to compromise either their own financial stability or that of their family on some romantic notion of a dream, good on them as well.
Human nature being what it is, the grass is always greener.
To me the knack is, work hard, look after your money that you've worked hard earning, then when your mortgage is paid off and your debt free you can start to compromise less.
As it is though most folk just get deeper into debt each year simply because they're consuming and buying newer crap cause they've convinced themselves they NEED to latest and greatest, phone, tablet, PC, TV, car, knife, sleeping bag, stove, tent, tarp, hammock etc etc etc.
I think the trick is to be ambitious enough to succeed in your chosen field, but logical enough to know when you've reached your limit.
I'd also say,
1/ NEVER meet your idols as most the time your disappointed
2/ NEVER start a business with friends or family members
3/ Never start working at something you enjoy, as most the time it'll quickly suck the enjoyment out of it
Lastly, who knows what you'll enjoy.
I would have though working outdoors would be my dream job, but when you HAVE to go out when you don't really want to it's not that much fun anymore day in day out.
Plus i wouldn't have thought for a second my current job would be enjoyable, as it is though i absolutely love it.
A big part of that is the people i work with though, NOT the job itself.
So it's easy to cast wide dispersions and generalisations, in the real world though things are always a damn site more complicated and intricate.