@wolftune said most of the things I would have, but I have a few to add:
Well, it depends. I would not consider it a big success if the goal were $1.
Then it would be a small success 
This difference is exactly why different projects need different goals, instead of a constantly-adjusting one. 100 patrons giving normal amounts is enough to make a difference in funding a small mastodon instance. It is not enough to fund Firefox.
For mastodon, the goal should be small enough that 100 patrons can reach it — otherwise we’re leaving money on the table. On the other hand, it’s a bad thing if 100 patrons gets Firefox near its goal, because those patrons will be wasting their money.
Say I am considering becoming the 101st patron of firefox, and I can afford to give $30/month. I am NOT willing to give that yet when firefox is so far from their goal. As you said,
why should i when they don’t?
…and this is really the heart of crowdmatching. It gives me a way to express “I am willing to give $30/month, but only when others are giving with me and it will make a difference.” If we automatically adjust the goal so that it’s always near 70%, I am no longer able to express the “but only” part… except by not joining the crowd.
Reframing the whole thing: I think it is a much better look to have 100 patrons of firefox, each giving 0.1% of their maximum (basically nothing), than to have 100 patrons of firefox, each giving 70% of their maximum, and still accomplishing basically nothing.
( This is a feature, not a bug 
)