Has a buyer attempted to go around you to buy directly from seller?

I am expanding my knowledge on wholesaling. I would not consider myself in anyway a wholesaler as of yet. While I am continuing to expand my knowledge in real estate as a whole, I am genuinely curious if this has ever happened to anyone? Going through posts on Reddit, Facebook, and other forums, I have noticed a lot of people say “you can’t trust anyone” and I often wonder who they’re talking about. Now, I know that when presenting a property to a potential buyer that we should already have it in contract to buy. Specifically, who can you not trust? Is it often a sole group?(agents, sellers, buyers)