Go for it!
I'm sorry if my rather glib, 'tongue in cheek' comments came across as negative.
The reality is that we fly because we love it. The bonus is that we can be paid to do so. But as with any job, it is a job, with all the downsides, so the joy of flying can get rather tarnished with time.
Becoming a pilot will always be expensive, but as with any other rewarding career or profession, it brings its own rewards along with its challenges. Your daughter should follow her dream, and she's very lucky to have a mother like you who is helping to support her.
As you rightly say, we all thrive on challenges. Professonal flying will deliver those challenges in spades - not least the worry of financing the training! The rewards should follow.
Best of luck to your daughter in her pursuit of her dream, whichever route she chooses to go. I had the same dilemma, and went both rotary and fixed wing. She will find her own path sooner or later, one that's right for her.
For both of your offspring - their determination and hard work will be rewarded if they truly believe in thier goals - go for it!
PM