In their defense, for someone who has never heard of Lemmy/the fediverse, it's reasonable for them to be cautious. So many other platforms are VC funded, do guerilla marketing, have hidden agendas, etc. It's especially bad on Reddit with all the AI astroturfing now.
I've seen a bit of that in the Canadian reddit comms, where new users are initially concerned that they're joining another american tech startup's platform. Once they learn how the network works, how the software is open source, and (specific to lemmy.ca) that the site is managed by a non-profit and the servers are in Vancouver, they're more excited about it :)