Well where are all the other free SSL/TLS certificate providers, then?
ZeroSSL sometimes gets mentioned, though they are also pretty keen to charge you, which is the exact reason why many go for Let's Encrypt: https://zerossl.com/pricing/ (admittedly, they're much cheaper than most alternatives, but you can't beat free)
Most of the other paid providers out there do see like they're just running a racket in comparison:
https://www.ssl.com/certificates/basicssl/
https://www.digicert.com/tls-ssl/basic-tls-ssl-certificates
https://www.godaddy.com/en-uk/web-security/ssl-certificate
It's an order of magnitude more expensive than just getting a domain, my expenses would be in the hundreds of dollars per year if I wanted to get the certificates from them, which I can't really afford while working in Latvia and having 30+ sites to manage across different domains.Let's Encrypt works and once it stops working (should that ever happen, which you kind of need to include in your risk analysis), I'm kind of screwed.