You will get tapped out by a lower belt, it is just a matter of time.

The best way to prevent this is to:

*Avoid lower belts that are getting better or giving you a tough roll

*Avoid rolling when you are very tired

*Avoid putting yourself in bad situations

If you avoid these things, you will be less likely to get caught
by a lower ranked belt.
But if you avoid these things, your development will suffer,
and your team will suffer.

The truth is, that it is no big deal to get caught by a lower belt.  Keep it fun, and keep rolling.