One of the concerns I always have about things I love is that they'll work but eventually disappear. Is there a way to donate/pay/tier for this? I assume it comes at non-zero cost to you in terms of time bandwidth hosting etc.
Open sourcing is more to enable people to be able to build the thing in the future with new libraries. OSes move forward every day and something that runs/builds today might not be able to run/build tomorrow, so open sourcing makes sure it's possible to change libraries/API usage if needed.