Yes, [D]DoS is a problem. Its not uncommon for a single person with residential fiber to have more bandwidth than your small site hosted on a 1u box or VPS. Either your bandwidth is rate limited and they can denial of service your site or your bandwidth is greater but they can still cause you to go over your allocation and cause massive charges.
In the past you could ban IPs but that's not very useful anymore.
The distributed attacks tend to be AI companies that assume every site has infinite bandwidth and their crawlers tend to run out of different regions.
Even if you aren't dealing with attacks or outages, Cloudflare's caching features can save you a ton of money.
If you haven't used Cloudflare, most sites only need their free tier offering.
It's hard to say no to a free service that provides feature you need.
Source: I went over a decade hosting a site without a CDN before it became too difficult to deal with. Basically I spent 3 days straight banning ips at the hosting company level, tuning various rate limiting web server modules and even scaling the hardware to double the capacity. None of it could keep the site online 100% of the time. Within 30 mins of trying Cloudflare it was working perfectly.