Can you just buy, sell, and repeat?

Will sound dumb, but I’m a tad confused as to why people don’t do this; BTC seems to fluctuate a lot within the 90s every month.

Thus, can I simply buy 1 BTC when it’s at - for example - $94,000, sell It at $97,000, thus gaining $3k? Then, when it’s down to, let’s say, $95,000, I’ll buy 1 again and sell it when it’s reaches $98,000, thus securing an additional $3k in profit, and rinse and repeat many times…

That’ll lead to thousands of dollars every month - assuming fluctuation remains as is or gets better.

I must be missing something. Educate me.