Yeah, I completely agree with you. One of my biggest influences is Joel Spolsky, and his advice on this is, "If it’s a core business function — do it yourself, no matter what." [0]
When I started the business, I thought the money was in the software, not the hardware. I figured people would build the hardware on their own, and they'd pay me to create a nice software experience for them. I offered hardware kits as a convenience for users who wanted to buy all the parts at once. Then, I realized people would pay more for custom parts, and I ended up with electrical engineering at the core of my business before I even realized what I'd done.
In the future, I'll definitely stick to software and domains where I'm competent at the core skills myself. But now that I'm here, I'm hoping to make it work despite having to outsource the EE portion.
[0] https://www.joelonsoftware.com/2001/10/14/in-defense-of-not-...