Yeah, that could works, do you mind to share what are those 5 coins? Are the coins btc, eth, ada, xrp, and xlm?
10% isn't a relatively high number, if you buy €1000 each, then it's €100 profits for each coin, and the 5 coins I mentioned above could increase more than 10% within a few weeks. Just make sure to set the buy and sell arrangement.
If that is the coins, I think people already buy those coins with a large amount and they are ready to sell them at the highest price. If the profit is just €100 for each coin, that will be no problem because he can make another profit from the other coins if he buys it. But if he doesn't have the other coins, he can wait for a while to buy back on that 5 coins to make another profit. But I am not sure if that coins can increase within a few weeks because that will depend on how good bitcoin will move in the market. If the bitcoin price does not move to the higher price and stays at the current price until the end of this year, I think the altcoin will also not move to the high price and be up and down for more. But we can use that moment to buy low and sell high to still profit in any situation.