If OneWeb wins, SpaceX makes a ton of money launching for them, and doesn't have to bother running an internet company.
Selling shovels is a great strategy, even if you own a gold mine.
They are competing for customers but, at least last I checked, they weren't putting a ton of bandwidth into orbit (compared to existing land based stuff). Maybe they'll both end up just selling as much as they can produce.
The limiting factor will be spectrum allocations. You only have so much bandwidth per area, giving an advantage to those that either have more directional antennas or more spectrum available.
Satellite internet has the opposite problem. If it ends up winning it will be a testament to dysfunctional governments around the world.