If you host your email on a VPS, you might as well let an email provider manage it all for you. In both cases, a company has access to your emails. What you have achieved is doing the dirty job of administration for the company, while not getting the privacy benefits of self hosting.
You have a trust relationship with your VPS provider. Yes, they can access it, if they want to. The difference is that with a VPS you have contractual privacy and with e.g. Gmail they outright tell you that they scan your emails. So it is a big difference.
With everything, it's question of budget and what risks you accept.
If you host it at home, can you endure uptime?