Well, Would you use a car that does NOT have any breaks???
Probably not! And you really should use a PROPER protection on your computer..
And the free antivirusprogram are NOT really that good at all.. And the one built into Windowss 10 is pure crap.
I have used it for a while on my seldom used stationary computer.. and while visiting some of the largest, ehrmmm: Adult webbsites
that crap did nothing, but when visiting the same websites on my laptop (that has a proper PREMIUM Sophos home antivirus program)
the sophos antivirus frequently alarmed of malware. And when checking the urls against virustotal they where malicious.
That continued with links in web-searches, Then i used google a lot. and has now changed to only using bing (safe search = off)
So I really would not recommend anyone to NOT using any proper antivirus (that means NOT using ANY free antivirus)
Note that there are a reason for the free antivirus to be just that: Free! If its free they really don´t need to protect you all the way
like they do if you paid for the protection.. And there are cheep and good antiviruses out there Sophos only charges €37 for a premium protection to be used in up to 10 different computers/macs.. (thats €3,7 per computer and year)
If you ever surf porn you really need to read:
https://securelist.com/threats-to-users-of-adult-websites-in-2018/89634/
45% of all porn themed threats where trojan-downloaders and yet another 20% where trojans...
And according to kaspersky:
"During the year(of 2018) , Kaspersky Lab solutions repelled
1 876 998 691 attacks launched from online resources located all over the world,
554 159 621 unique malicious objects were detected and
21 643 946 unique URLs were recognized as malicious by web antivirus components." Read all about it
HERE
So relying an a FREE antivirus (like the one incl. in Windows) is in my mind, just like using a car that you know does
not have any breaks.. (=stupid!)