1. You're not the only one that's underpaid.
It bugs me to no end when musicians complain about being the lowest paid workers in modern society, or use it as an excuse to not be generous because they "just aren't making enough money".
Waiters, busboys, landscapers, and a whole host of other jobs pay as much or less then musicians typically make, so let's stop pretending that we're the only underpaid segment of the workforce.
2. Nobody owes you a living.
I believe in making great art. I'd even endorse making great art that is never recognized, or paid for in this lifetime. But if your art is noncommercial, the sad truth is you will not be paid what it's truly worth.
As musicians, we're wasting our time if we let ourselves dwell on the fact that were underpaid for the great art there we are creating.
3. You signed up for an alternative lifestyle. Deal with it.
That means that your lifestyle will probably not match any of your friends, family, or even neighbors. You're probably going to take a lot less vacations. You're probably not have nearly as many nice things.
Instead of complaining, I suggest one of two options: stop complaining and focus on what you do have and the advantages your lifestyle offers, or change your lifestyle. If you have a career in music, it's probably a good guess you'll be able to have a career in something else that would pay more. Who knows? You might actually be super happy with that corporate job (and honestly, that's not sarcasm).
4. Don't be surprised when nobody knows what you actually do for a living.
I have several friends that are electrical engineers. I know almost 0 about what they do every day. It's not that I hate them or I'm uninterested, it's just way out of my realm of experience.
If you're misunderstood, you're in good company. Almost everybody doesn't know what everybody else does.
5. Stop pretending that music is a "higher" calling than any other job.
Music, at its best, is great art. So is cooking, painting, dancing, engineering, architecture, gardening, quilt making, and about 4000 other disciplines. as musicians, we should never live with the illusion that our art is above other's art. Not only does that arrogance blind us to the beauty of other disciplines, but it also gives us a sense of false self importance.