How is it possible that people who claim that they did not make any mistake lost cryptocurrencies?

I very often read here and on various other subreddits about cryptocurrencies posts like - Need help, Please help i lost my funds, I logged into my metamask account and there was nothing, etc. How is it possible?

I assume these people are not lying, or are they? How is it really possible for someone to withdraw cryptocurrency without a verification code sent to e-mail or sms? I ask mainly because I personally use a Trezor wallet. Of course, the seed is not backed up anywhere on the computer, nor anywhere online, but it is stored as it should be. I use Trezor Suite from time to time, but on the computer on which I surf the Internet or work. I don't correspond with anyone, and I don't get involved in anything, so I'm not afraid of a scam, I'm afraid that one day I'll go look at my crypto-savings and see that they've all been transferred to an unknown wallet.

What should I avoid? What else can I do for the security of my crypto-currencies other than that they are in Trezor and the seed is stored on a real piece of paper.