Agreed, but data is so easy to find online! My breakthrough was that Python comes with SQLite built-in. Pointing DuckDB at a CSV file looks even easier.
sure, you can find data and spin up your own db but you still need a tutorial to a) explain what the data/tables are and b) guide you through some things to build. for most programming languages you can make some sort of little widget or itneractive program that lends itself well to learning via curious exploration. SQL does not lend itself to that because you don't really make something 'fun'. You just make more tables. People aren't going to naturally come up with the kind of boring-but-challenging things that you use SQL for like "come up with a daily aggregate of pageviews, but exclude users that had account status X in the previous 30 days OR if they have a special status set in this other table as of the date of the pageview. And make sure that days with 0 page views show up with 0 pageviews and are not just missing from the table".
Also, it's very easy to make queries that complete and look correct but give wrong or incomplete results. You've not going to notice that from just running queries in self-directed practice.
From a slightly different perspective, some people like these tasks :). That's part of the mindset of being a good data engineer, for example - I rarely have a problem coming up with my own set of queries to try out a new database or dataset. But I'm also not really interested in a lot of SWE-specific things.
Maybe this just isn't something you really want to dive into. That's ok!
Forget online tutorials, you want to pick up thick red Wrox SQL books from your local used bookstore or co-op. Nobody selling you anything, densely packed, comprehensive info.
SQL has changed very little over the past 25 years, and while there are some syntax variations across different databases, the most important 80+% is universal. Even if the book is for SQL Server the vast majority will work on Postgres, SQLite, etc.
https://docs.python.org/3/library/sqlite3.html
https://duckdb.org/docs/data/csv/overview.html