A billionaire just offered to fly me to London out of the blue.

Actually, not just me, but all the core team members of a project I
run, so we can meet and work face-to-face for a few days. These team
members are all unpaid volunteers and all live in different time zones
and I've never met most of them. So it will probably be really useful.

The strange part is: he funds a team working on a competing project.