Why is everyone in this new space race trying to cram themselves into the same niche, instead of synergising with each other?
Everyone trying to become an Earth orbit launch provider is too late; SpaceX has the lowest cost, highest capabilities, and perhaps the best reputation.
Rocketlab is one of the few companies that is being smart and trying to operate outside of SpaceX's capabilities; they're actually cheaper for tiny satellite launches, and aiming for cheap operations beyond Earth.

For now it's probably impossible to make a profit off of launches beyond Earth, besides launching probes for researchers (which I figure there's very little money in). So you can't fit a bunch of money hungry space companies into that niche.

So what are some profitable niches?
Well, it's important to remember that the reason you can't get into earth orbit launches now is because they're cheap and will get a lot cheaper. Starship will make it viable to construct multi-kilotonne structures.
So why are no companies planning to build space stations? If space tourism will be a thing, a space hotel is a must. Refuelling stations or attachable boosters in orbit could become a valuable part of a more complex space logistics network.