As someone who has started and operated a bunch of companies, I see this model as having a couple inherent challenges up front. (This isn't in any way to disparage DP, I'm a huge fan and remain a preorder for as long as it takes.)
First, the market size is never high enough (even Stern) to attract investors who normally are interested in a future exit (such as venture capital). The total revenue/addressable market is not high enough to model out the multiples needed from this group. (It's not that there isn't huge profits to be made, just VC types want businesses that show a path to $100M's in revenue.)
Second, it doesn't attract lenders/banking because, as is the case with many manufacturing business plans, the asset to liability ratio isn't good enough for this banking climate. This wasn't true 30 years ago, but unfortunately has been since the 90's.
Therefore, there are only two ways to build a sustainable, medium-sized pinball business organically:
1) Have a benefactor who is willing to wait years to take a percentage of profits. This would come from someone with strategic interest or hobby interest with a large pocketbook. I know people who fit this concept but it's exceedingly rare. This can include a large media company or corporate interest who is willing to lose money for some intangible benefit (i.e. a movie studio).
2) Pre-orders, which in theory funds the build. This business model is fairly recent in history, so there isn't a lot of data about how to de-risk it. Kickstarter popularized it but there are only a few real scaled up success stories (possibly Tesla).
I think option 1) is ideal because you can build product you product in stealth and ship immediately upon release, which for this community, is less engaging but probably best. Option 2) is fine but the capital required to build the business is far too high for what we've seen these pinball companies charging. I've modeled it, and from what I can see, the price point would need to go up by 50-100% to build a boutique business, or the volume would need to be at Stern level to get to scale. Crossing the chasm is super difficult.
I can't blame companies for choosing option 2 because it's super hard to raise capital. My best guess is that if chose either 1) or 2), you still need about 3-4 years to get to breakeven.