There are several ways to do this:

1. Peer-to-peer exchanges like Robosats, Bisq, and others

2. Local meetups - exchanging contact info with other bitcoiners IRL

3. Bitcoin communities - like the best community in Bitcoin (Living in the Future 😏)

For real though, our LITF community is second to none.

I've bought and sold bitcoin plenty of times with other bitcoiners in the group. This week I bought some from a fella in Ireland who needed cash for a family trip.