Can you offer freelance services, programming, consulting?
Could you build an audience/sell info products/courses to teach something you understand very well.
Could you share information in a blog to get enough traffic for ads/affiliate sales.
Could you teach an online course related to your profession or write online course for a certification exam you have passed.
Think about what skills, knowledge you have and what would be valuable to others. Offer free advice, write a blog, start getting more involved in the community where people would find this valuable.
Try different things to find what works for you and what you enjoy doing.
A few quirks: - Depending on gambling laws of your country, it might or might not be possible to do matched betting - It's not a constant source of income, it decreases over time as you can only exploit welcome bonuses once and bookmakers stop offering promotions to you after they realize you're not a fish. The year I started doing it I was over 4k euros yearly income, now I'm happy if I can get 2k. Still, I'm happy with the amount I get, its a good chunk of my income but for someone with a high salary might not be worth it. - The coronavirus pandemic slowed things down quite a bit, since currently there are few sport events. So it might be not the best time to start doing it.