Because buyers choose to spend less money, so if a business comes around that can offer the same product/service at a lower price, the investor will want to own a piece of that business rather than the one that is about to lose buyers.

Right, because we never see investors making decisions that are suboptimal in the long term because they're too focused on short-term gains. Everyone is perfectly rational, and high initial costs have never discouraged anyone from trying to displace an established dominant player; it's purely because the dominant players are perfectly efficient and don't ever try to rent-seek.