Of course you can sell all the coins and save your money, maybe it will be correct, then you can buy coins at a lower price.
But what's the point in doing that? If you hold some bags, instead of getting out, you should buy those same coins so that if they rise, your gains will eliminate your losses (and you might even get profits if they pass your initial buying price), granted you have invested your money in worthy cryptocurrencies, not some shitcoins. Patience and longterm thinking work the best if combined with a plan/strategy.