Also to note:
Until recently (in terms of world history), there has never been an affordable way to internationally market and advertise a musical instrument or studio electronics. In the 80's and 90's, you'd have to take out an advert in a magazine, or supply enough mom & pop stores with at least one of your production units so they could demo it.
Website, youtube demos, maybe some internet marketing. But that's relatively cheap compared to the hard costs of designing brochures etc.
On the physical side, surface mount electronics (the types we see in our smart phones, computers, etc.), have lowered the cost of production, taking away a lot of the hand soldering necessary for vintage keyboards. The cost of development has come down as well, with design tools now available on everyone's desktop and rapid prototyping with affordable one-off circuit board manufacturing being very affordable.
With all of that, synthesizer sales are higher TODAY than they ever were in the 70's, 80's, 90's, etc. Smaller and smaller companies can now slice off a livable profit from their endeavors.