The value of a brand is derived from its exclusivity. If you making 10x bigger, then a degree from there won’t be as valuable.

I’m not saying that is right, but most exclusive colleges do brand management based on exclusivity.

The value of Harvard is in its exclusivity. If they just let anyone in over some SAT/GPA cutoff then the value of a Harvard diploma drops.

Because there is potentially merit in having institutions that are concentrated with the most talented. Not that it necessarily works out that way in practice, but 10x would entail lowering admission standards.

The number of people “qualified” to go to Harvard is probably more than 10x the current capacity of Harvard, though. Maintaining scarcity/exclusivity in the brand is more valuable than servicing the number of people technically qualified to go there, from Harvard’s perspective.

Yes, but many of those people choose to go to other prestigious schools. If Harvard admitted 50% of applicants, I don't see how you can claim quality wouldn't suffer.

I claimed no such thing :D

You said that they should admit 10x. Presumably that would mean 50% rather than 5%. I think quality would go down, you said it wouldn't. Seems clear cut to me.

Or allowing people who are equally as qualified get in? My understanding is the issue is capacity and not quality.

Qualification is a continuum, there is no such thing as "equally as qualified." Regardless, if Harvard accepted 50% of applicants rather than 5%, the student body would not be equally as qualified.

Same reason why clubs want to be exclusive and keep a long line of non-VIPs outside waiting to get in.