Ahh, another one.
I appreciate the lesson and understand that wisdom also comes with age. I don't dismiss that - in fact I realize and acknowledge that. That's why people have mentors, people with decades of life experience to learn from.
"Learn to distinguish between people who treat you well because they respect you, and people who treat you well because you're running half their business for an intern-salary."
Perhaps that is something you did not learn in your youth, but you should know that does not mean that those of similar youth age don't realize that. Personally, this was a point I exploited when I ran my business. Having interns that were years older than me doing work for me. Quite "amusing", as you point out, now that I think back...
Nevertheless, I think your advice is true. Lots of people out to take advantage of young people. This is not new, though and anyone with the level of experience in business having done work previously in youth years would know this.
The pattern that I've noticed is most people will speak similar to you. Those that don't and truly appreciate it were once young entrepreneurs themselves and experienced their levels of 'success' so they understand it. Though perhaps I just choose to surround myself with mentors of that particular quality.