Nobody is forced to use gmail as a provider. Remember it’s a free service with less commitment to you than a pay as you go mobile phone.
Anyone can buy their own domain and there are many providers who will provide email service.
Anyone can buy their own domain and there are many providers who will provide email service.
The vast majority of email is hosted by one of the large providers these days and if people can't reply to you the utility of your address is lessened.
Fortunately that's not at all what having a personal email is like.
First of all, you can always receive email no matter what. Nobody is blocking that.
Sending it to some larger providers requires configuring everything correctly, but it's not rocket science. Lots of people (including me) do it with minimal effort.
Finally, having your own email (domain) doesn't require self-hosting it if you don't want. You can always delegate that part to some provider. But you control the domain so you can switch providers (or switch to self-hosting) any moment. You can also do a hybrid option where you self-host receiving but farm out the sending, if you prefer. So many options, all of them work!