The price will go down, because this spike wasn't caused by new money entering the system, but by moving around of some money that was already in the system. And it's not a lot that's in, so it was only a matter of time when the rise gets exhausted and starts to fall back. I think that we will see some low volume aftershock waves today, and maybe even tomorrow, but it won't be long when the price drops back to sub 400. As long as there isn't new money coming in, then it's a bad call to just sit on BTC. Only thing to hope for is that the drop will be fast and not slow and ugly, like it has been for the past months.
What's this concern with the money entering the system being "new"? It's as if you think all of the people who cashed out during the double ATH withdrew to their fiat accounts and have washed their hands of Bitcoin. There is
a lot of money on the sidelines.
By the sounds of it, my advice to you would be to sell all of your coins and never come back. Surely it's the end of Bitcoin since no new money is coming in and it's going to be a slow grind downwards. The peanuts you'll earn trading isn't worth the risk of losing your capital. Just leave now and keep your money safe.
First we have to look at the constant stable supply. In the last 24 hours, 188 blocks were mined with 1 block bringing 25 new BTC into existance. Now we get that 188 * 25 = 4700 new BTC came out that need to be bought or held. With the current prices, most of it will be held not sold, because you wouldn't get any ROI and it has been like that for several months.