I think you’re under-appreciating the beauty of the exponential pledge schedule! If you’re Richie Rich and it takes $2430 to motivate you to practice guitar, that means that you derailed at all the previous amounts – $0 + $5 + $10 + $30 + $90 + $270 + $810 – which adds up, not coincidentally, to exactly half of the $2430 you now have at stake. So you coughed up $1215 but now you’re at the ridiculous pledge of $2430 and that should keep you practicing for years without spending another dime.
For me $810 tends to be the point where I consider it out of the question to derail and diligently stay on the road indefinitely.
It depends a lot on the goal. I just called $810 my motivation point but that’s for things like writing blog posts (classic case of a “one more day won’t matter” slippery slope of doom). For my pushups goal, $5 or $10 is plenty because it’s too silly to pay really any money just to not do some damn pushups. If I just set alarms or something I’d never follow through because I wouldn’t feel like doing them at that moment. I always prefer “later” or “tomorrow”. But a small nudge from Beeminder suffices to make me just do them.
Maybe the real counterargument to your theory that Beeminder’s motivational schema is self-defeating as your wealth increases is just the case studies like PhD theses that wouldn’t have happened without it. We know of many massively high-value things that Beeminder made possible (not least of which being Beeminder).
Or maybe the most fundamental counterargument is that Beeminder is profitable, and unless these premium changes have generated a jump in short-term revenue by cannibalizing long-term revenue (we’ll learn that soon!) then we’ve now achieved what we hard-committed to for 2016 for Beeminder to survive into 2017 and beyond. Phew!