I wonder why there aren't popular free/open projects that do what Komoot does. What they did above the contributions seem to be doable by a dedicated group or a nonprofit.
Honestly the best course of action is to let it die. $300M is enough money that losing the user base would be enough for similar things to stop happening.
(I've just commissioned a designer for a bit of a refresh, so it should get a _little_ more polished soon!)
Well, there are still costs involved (not just financial but also labour), and someone has to pay them. We are lucky to have a number of great open source and community-driven projects where people do contribute time and money to make data freely available to everyone, but it's not guaranteed. If there aren't enough people who are willing and able to contribute, or the costs get too great, the project will founder.
OpenStreetMap seems like it is already doing this to an extent, or at least is a good platform on which something like this could be built. Hopefully this saga encourages more people to contribute that way.