But wouldn’t it be a failure if it’s bullshit and therefore no gains?

Not if you sell before the other fools.

A16Z's post on the Slack IPO (https://a16z.com/announcement/slack/) is a good pointer to the kind of thinking here. A pivot from an unprofitable game to laying off 80% of the company to a weird communication app could be fairly described as "bullshit", but when your business model is finding the rare exceptions where the stars align and a company ends up being worth billions, it's not a kind of bullshit you can afford to be entirely unreceptive to.