Probably false.
People don't find flimsy excuses to refuse conventional life-saving treatments, and non-conventional treatments can become conventional (say, antibiotics). This holds, though less so, even if the treatments cost quality of life and money.
I didn't start out liking life, but I seem to be very atypical in that regard (often suffer from anhedonia, for example). But it's more likely that I've moved away from the norm, not toward it, especially since I'm bad at distinguishing norms for X from norms for "X"... shudder
Scary. Someone please disprove this.
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: