Some people are using a database for a single user, on a single machine. They don't want or need 1000+QPS, live failover, or massive concurrency. They just want

Some people are using a database for a single user, on a single machine. They don't want or need 1000+QPS, live failover, or massive concurrency. They just want something simple that works. The Chrome browser stores many pieces of the user profile (bookmarks, browsing history, etc) in SQLITE databases. I'm not sure if you consider that "professional".