Because my ex boss blocked me from a promotion because I was her best worker.

I was working support, and was learning full stack in my spare time. Showed the Devs in the company some of my projects, and that's when they wanted me to work with them, since I already knew the system. Since I was rejected, I found a dev job within 2 weeks, and handed in my resignation. My manager was furious and asked why; the look on her face when she realised that it was because of her was great.

Now working as a fullstack developer for 4 years.

Fuck you, Lena!