Ask HN: How to reskill without losing income?

I am making a good living with a niche skillset. It's a fairly old technology and there's less and less work in that area. I'd like to move to another technology stack - it's not too hard for me - different keywords etc and I've actually done some hobby projects already. I think if I applied for a job I'd get rejected as there is no track record of being able to work with that tech. Best get case I could probably apply for a junior job which would pay well below my current. It will probably take years to get to the same level of pay, assuming that particualr tech stack takes off. Is there any eascape from this? Are there any companies that would be willing to hire a grumpy 30-something and recognise his/her experience as something reusable?