Let’s start like this, English, great and fascinating as it is, it’s not the world. Germany has diplomatic discussions with Austria and they don’t do it in English, just to give you an example.
German is complex and precise in ways that English isn’t. English is great and if you can speak it, you should enjoy the huge advantage, but German is surgical. It’s totally accurate. The grammar leaves no doubt what you mean, and in a way, it’s a metaphor for a way of looking at the world that you wouldn’t have really known about had you not bothered to grapple with its glorious complexities.
Learning German permits you to shock Germans. They think their language is impossible for foreigners, and to some extent they are right. It can be very tricky. But like the enigma code, it’s possible to crack it, and you don’t have to be Alan Turing to do it. You need determination, a great teacher and bingo, you’re in.
Knowing German makes you fearless. You can speak German. Mandarin? Bring it on! The first time you speak to someone ‘auf Deutsch”, it’ll be an enormous boost to your self-confidence. You become fearless.
German opens a window into another culture. It’s not a totally foreign one, and there are plenty of overlaps into the Anglo Saxon world, but it’s really not the same. The first time you understand a joke or a saying or an off-the-cuff remark, you get a huge, warm, rush of pleasure. A bit like your first ‘Currywurst”.
The other great advantage with learning German is that people think you’re clever. (That’s always good, however, we know you are!) British people think that if you know what a pronoun is, you are Superstar.
So, there are many more positive notes, but may be you should try it yourself.