Several reasons:
1. They're sold on a lie. Here's a photo of my laptop in front of a beautiful pool, next to a delicous bowl of $1 Pad Thai. Ignore the February burning season and total inability to communicate with anybody outside of self-deceiving 20-something Westerners like myself.
2. There are benefits. Being a DN is freeing and fun, especially if this is your first shot at remote work. You don't justify to anybody what time you have your sandwich in the morning.
3. Most DNs have never experienced actual loneliness before, so they don't know how crippling it is. They think all their friends and family having been away/busy one weekend or even one month was loneliness. That's like how the people in 5-day COVID hotel lockdown thought of themselves as having experienced imprisonment. Sure, only in a glancing sense.
4. Sex/romance tourism. Look at the hot exotic naive foreigner who's here to exchange some emotions/experiences with you, the hot exotic native person who's otherwise boring or too slutty/free-thinking for people in your own country.
Being a Digital Nomad is a life experience that comes with as many negatives as positives. But there are positives.
Why do people do it? Because the alternative is to never have done it.