Personally, I don't think paid services are necessary. Windows Defender is more than good enough as a primary antivirus, especially when used in conjunction with Malwarebytes and good browser add-ons (uBlock Origin, NoScript, HTTPS Everywhere, etc.) The less third party programs you have in your computer, the better; you never really know which ones spy on you these days, and they could easily end up being vulnerabilities themselves.

One thing to note though, is that no matter how protected you might think your system is, you still shouldn't be clicking random links and downloading random files. Better yet, you should have a separate system (dual boot, live USB OS, Raspberry Pi, etc.) just for crypto and/or financial stuff, so a single misstep doesn't end up costing you thousands of dollars.