Well, aren’t you high and mighty?
I don’t know what kind of “people” you’re hanging around with, but it sounds like they’ve made you pessimistic about others who actually do have wild ideas and work tirelessly with real ambition and real passion.
If you love something enough, you will succeed at it. You will force your body and mind to do the work, and eventually, you’ll do it well. It sounds like these “people” you’re talking about are so detached from their sense of personal fulfillment that they don’t know what to pick, so they just say, “Painting! I guess I’ll try to paint!”
Regardless, it’s not up to you to tell them not to try. It’s up to them to fail and decide to try again or not. Please don’t pretend to know everything about “other people.” They can and will surprise you.