Is that something you factor into your playbook? Or do you simply not find it relevant to judge whether to enter a certain space?
Assuming that you're not a commodity product, it all kinda nets out in the end. If you have a competitive market, you have proof that people want your product at a good price, else no one would be in the market. If you execute better than all of your competitors, then you can theoretically take every last penny of that market.
I don't think the competitive pressure changes the decision whether there's revenue to be made in a certain space, though it may change the personal decision if the operating tactics required in a competitive market are personally fun for you the human being.
That said: A good market will become crowded quickly in either way.