If you play "what if" and imagine the Japanese had won Midway, and the US had no carriers at all, that gives the Japanese total control of the Pacific. The Japanese can take Hawaii if they want to, because how could the US possibly reinforce and resupply it? The Japanese can attack shipyards and ports on the West Coast at their leisure - and those would be defended obviously, but the attacks would greatly slow the progress of shipbuilding.
Fortunately for the US, they have other ports in the Atlantic. So okay, the US builds carriers there. Now the problem is, you can't just build one carrier and send it to the Pacific. If you have just the one carrier, the Japanese will be very eager to sink it. They'll have spies and recon subs so they'll know when it sorties. If you try to take it through the Panama Canal they'll ambush it.
The bottom line is, you have to build several carriers before you even think about challenging the Japanese again. That means you're looking at years - YEARS - during which, the Japanese do whatever they like. And when you finally put a carrier task force together, at best it's a fair fight ...you might lose again.
And don't forget, while all this is going on you're also fighting Germany.