This is already very common, by the way. Most churches and renovations of churches are paid for by the parishioners (who own the church) just giving money and hoping that they actually get a church building out of it and that the builder doesn't just grab the money and run. That is why builders put a lot of effort into establishing a reputation.

Look at the Frauenkirche, in Dresden. Over a million people donated money and it costed almost 200 million euros. Which would be almost 3340 BTC. And they got nothing back but a church. And that made them happy. Now they have a church and they go to the church and people come from all over the world to admire their beautiful church. And the businesses in the market around the church sell church models and church postcards and people sit in the cafes and sip overpriced coffee to admire their beautiful church.