Probably this is the feeling of the new investors who didn't yet understand how investing in crypto works. As a crypto investor, we should know from the start that there's a risk upon your investment. The volatile market makes your Bitcoin amount value fluctuate but actually, your Bitcoin will remain the same, so nothing to worried about. If you invested 1 Bitcoin it will remain 1 Bitcoin, if the value towards dollars has been decreased, you should wait further to see your profit. Don't sell when the price is low, that is insane.
Getting nervous is normal, but don't panic and hold your Bitcoin until such then you will successfully get your profit.
Funnily enough, having control over your emotions ain't even just bitcoin/crypto-specific as a lot of people think; it's actually for investing in general, and it's been a really really common advice for decades.
Here's one famous quote from Benjamin Graham(author of The Intelligent Investor, Buffett's favorite investing book):
"Individuals who cannot master their emotions are ill-suited to profit from the investment process.".
^and this dude died in 1976. This advice has been THAT old.