Yes, only a small number of companies produce memory because of capital requirements and complexity. When prices go up both of those things become less of a problem for investors who can see better return for lower risk on that high capital investment. They will then invest in production to capture those returns. This is literally the exact reason Samsung are doubling supply of this particular type of memory.
Memory factories cost billions to tens of billions, "investors" aren't going to spend that kind of money if they are not reasonably certain that they are going to make a profit, and the market is very uncertain right now with everybody bracing for a bubble burst at any moment. It's not the first time there has been such a shortage in the computer parts market, and the oligopoly, be it RAM or hard drives manufacturers, has always managed to keep prices high and production low enough to avoid a price crash after recovery.
Yes, only a small number of companies produce memory because of capital requirements and complexity. When prices go up both of those things become less of a problem for investors who can see better return for lower risk on that high capital investment. They will then invest in production to capture those returns. This is literally the exact reason Samsung are doubling supply of this particular type of memory.
High prices will fix the shortage.