Your question contains a faulty assumption:
During crashes and corrections the amount of sellers is of course higher than the amount of buyers, making it difficult to sell stocks.
This simply isn't true. Every trade has two sides; thus, by definition, for every seller there is buyer and vice versa. Even if we broaden the definition of "buyers" and "sellers" to mean "people willing to buy (or sell) at some price", the assumption still isn't true. When a stock is falling it is generally not because potential buyers are exiting the market; it is because they are revising the prices they are willing to buy at downward.
For example, say there are a bunch of orders to buy Frobnitz Consolidated (DUMB) at $5. Suppose DUMB announces a downward revision to its earnings guidance. Those people might not be willing to buy at $50 anymore, so they'll probably cancel their $50 buy orders. However, just because DUMB isn't worth as much as they thought it was, that doesn't mean it's completely worthless. So, those prospective buyers will likely enter new orders at some lower value, say, $45. With that, the value of DUMB has just dropped by $5, a 10% correction. However, there are still plenty of buyers, and you can still sell your DUMB holdings, if you're willing to take $45 for them.
In other words, the value of a security is not determined by the relative numbers of buyers and sellers. It is determined by the prices those buyers and sellers are willing to pay to buy or accept to sell. Except for cases of massive IT disruptions, such as we saw in the "flash crash", there is always somebody willing to buy or sell at some price.