Publishing wide vs exclusively

Apparently, this is an extremely important question authors must ask themselves. Do you want to be on all platforms or just one?

If you publish on Kindle Unlimited, you can’t publish the e-book anywhere else.

If you publish on, say, Amazon, you can publish elsewhere at a later time should you choose to.

For me, I want my book on as many platforms as I can. I’m writing to a very narrow niche as it is. I feel it would be akin to shooting myself in the foot if I just picked one platform.

But I need more information!