I've been using my own domain with a catchall for over 10 years and never had problems with spam. Spammers tend to send to harvested address lists, not just try to send to random mailboxes for a domain.

I forward my catch-all to gmail so I get they're great spam filtering while preserving the ability to switch off of them instantly should I decide to in the future.

Been running my own mail server with this setup for over 10 years. This really hasn't been a problem for me at all... Yet