I work in an organisation that has a large technical debt. The organisation manages at least $A60b of member's assets, and is overseen by the Australian Tax Office. It also is very visible politically. These three factors make it extremely conservative in terms of change.
However, change is imposed on it inevitably from the outside, so instead of making large-scale changes to its architecture, it tries to keep up with the market by making thousands of small hacks. The original architecture was not designed to cope with this, so it has become hack upon hack upon hack. I should be employed (and paid above-average) in this jobs for decades to come.
Sounds like a system I worked on for an investment bank. Sure you will be employed for years fixing hack upon hack, but its not very rewarding work (in the non financial sense).
Don't underestimate the value/reward/fun/etc that you can get from a fresh project. New problems, new development process, the chance to re-iterate past designs and architectures, integration with existing/old/legacy systems, and a host of other things.
That's my bit of advice to you on that, as it reads a bit like you're very comfortable and expecting it to stay that way for "decades to come".
I do work on my own projects that are fun and interesting. But nothing beats a regular, permanent high-earning job, no matter how boring it is. I personally know a couple of developers who are stressed financially after working for "fun" companies.
However, change is imposed on it inevitably from the outside, so instead of making large-scale changes to its architecture, it tries to keep up with the market by making thousands of small hacks. The original architecture was not designed to cope with this, so it has become hack upon hack upon hack. I should be employed (and paid above-average) in this jobs for decades to come.