Should I Use Chessbase?

I have been working with ChessBase since 1991. I have won an uncountable number of games and many tournaments due to professional preparation. A database with 2500 well-annotated games of mine is my special treasure.

At your level I would say no. Unless you really need offline access to chess databases and database tools, you don't need it. Lichess studies + the analysis board + chessgames.com + https://chess-db.com/public/index.jsp are all free and more than good enough to do anything you would want chessbase to do.

Opening preparation is over-hyped, what difference does it make if your opponents know zero theory and just play random moves. Understand the openings, don't memorize

You would win the game if you knew the ideas behind the opening, not because you memorized some lines that you did not get to play. I for example know quite a bit of dragon sicilian theory, but 80% of online players play some random moves, so I have to win based on my understanding rather than memorization. This is my point also with over-hyped, people really shouldn't focus on openings as much as they do, I win most of my dragon games because of favourable endgames I achieve rather than anything else

I get great positions out of the opening all the time. I throw my advantage away all the time too 😂

Don't underestimate the openings. But some answers already mentionned the important thing which is to understand the plans and ideas associated with your openings. If you neglect openings, you may develop bad habits like playing for tricks or play a bad line over and over again or just been lost and not having a clue on what to do. I had this problem recently while playing against the London System. Not an easy beast to tame when you are a Nimzo-Indian player because those 2 openings don't share the same ideas. Database won't tell you a lot about ideas and plans unless you are strong enough to decode GM games. So you need to find this info in games analysis. Seirawan's and Akobian's videos (St-Louis Chess Club on youtube) are an example of great analysis.