Stop thinking of it as a race to 50%.

Instant runoff is really progressive elimination down to one person.

Run round 1. Drop the person with the fewest votes. Anyone who voted for that person drops to their second choice. Run round 2. Drop the person with the fewest votes. Anyone who voted for that person drops to their second choice, or out of the voting pool. Run round 3, etc.

In practice people just stop when someone has over half the votes remaining in the pool, because you are guaranteed who will be the last standing.

There is no perfect voting mechanism. Yes, there are scenarios where it produces no good answer. But it works a heck of a lot better than what we use.

Cheers,
Ben