If you wait for confirmation you are fine. But for 0-conf here's an explanation of how a double spend can be done: https://jasonc.me/blog/bitcoin-bip-133-double-spends-bch
I'm reading the jasonc. The double spend depends on some miners filtering out low fee transactions. Off hand I don't see a need to filter out low fee transactions.
One reason is by setting a minimum they encourage higher fees and make more. Another is that some fear low-fee transactions can be used for spam. Majority have 1 sat/b minimum.