I agree with you as far as startup costs go.

But your example is only if you only boulder indoors. Costs add up quickly if you want to move outdoors and want the flexibility to do a variety of climbs.

You can easily have a couple thousand dollars in gear.

Harness $70 Belay device $20-150 Rope $150+ (possibly multiple) Quickdraws $10-14 each, you probably want a dozen or so. Some slings Some carabiners

That'll get you outside and working on bolted routes.

Then you get into climbs that don't have man made bolts that you can clip into (trad climbing).

Each piece of protection at this level costs $60-80 new, and you'll probably want like 10 of them at least.

And it goes on and on.