Tech books used to pay a much higher royalty than "regular books", like novels. I'd get 14% per book vs. 7% or less on a novel. That can make quite a bit difference. Of course, people will tell you to self-publish and keep next to 100% of your profit, but the gatekeeping function of publishing houses can be beneficial as well. I've had a few instances where I thought I had a fantastic idea, only to go through "the process" and see how it wouldn't have sold much.
That said, and I may get some heat for that, self-publishing only makes sense (if you're not just in it for the fun of typing and researching) — if you have a large-enough platform. I'd even argue that 95% of your success will be having a fantastic platform to launch this from, and 5% will be about the contents of the book (if you're self-publishing).
Pieter Levels could launch a photo book of his favourite cat photos, and still make a 100k off of it. Most people can't do that, because they don't have the platform.
This differs quite a bit with publishing houses. If you can get in, and it tends to be easier in tech writing as those books can be priced much higher, then they'll bring the platform, and you just bring the content. Once launched, you can build from this "borrowed" platform and try to work on your own audience. My unsolicited advice here would be to make as much as you possibly can (executing as quickly as possible) from that initial launch power and build a crowd around it that you can use as a firestarter for future projects.
Depending on which publishing house may offer a deal, this could mean being placed in most universities, being placed in large-chain book stores all around the world, or airports (for novels). Something that can rarely be done by self-publishing.
Again, not hating on the self-publishing route, especially when you look at the per-book numbers, where it's 14% or less before taxes vs. close to a 100%, but if you don't have a platform, then you'd probably need to be super ready for spending at least a full year on this to get it up to quality, and then also building a platform to launch it from. Just the title and name doesn't cut it anymore, unless you do get really lucky.
Hope this doesn't offend those who self-publish, if you're doing this successfully, you are the true masters. Finding a publishing house is, in my opinion, actually the easier route.