@angeleyescj ah I see, I may have misunderstood what you meant then. those are all valid concerns, and you can solve for them. Because it's hard to predict any of those (except D, disregard D when starting out), although you may be able to reasonably assume some numbers, I'd use the "worst-case scenario" framework (also called maximin approach) and create a world where you can live with the worst-case scenario.
For example, let's say you put in all the work to do a crowd-funding campaign, you hit your goal, but every single customer asks for a refund within 3 months. What's the worst-case scenario? Well let's say you invested in manufacturing each order, without considering returns, then you'd be out that total investment, which may be something you can or cannot live with. If you cannot live with that worst-case scenario, solve for it. Create a refund policy, manage expectations up-front by telling customers it'll be 50% longer than you think it'll take. You could also only invest money for manufacturing after the refund window has concluded. Once solved for, re-evaluate the worst-case scenario. Let's say you've decided the you don't want to lose any money, and you've created a no-refunds policy. You won't lose any money in this case, assuming that you hit your goal. If you don't hit your goal, you also don't lose any money. Seems decent.
This applies to all levels, too. If you zoom out and think about your choices of crowd-funding vs VC funding.
Crowd-funding: worst-case is that you spend a bunch of your effort and you get crickets. You learn new skills, you then build on those skills and take another swing in the future, iterating on something that you assume will significantly change the outcome the second time. You lose little to no money.
VC funding: worst-case, you spend a shitload of time trying to raise money and you don't get any. worse yet, you can't spend the time you need to on the most impactful skills when it comes to marketing, customer research, etc, because you're trying to raise. If you don't raise in this scenario, you likely don't have a business, since you predicated the entire project on raising money.
VC path sounds like a shit worst-case scenario to me, because I want to play the game of entrepreneurship as long as I can and build skills while "staying alive" aka in business. I also think you need to go full-time if you go the VC path, compared to part-time with crowd-funding and bootstrapping, at least to start. The paths can change as you go, since the worst-case scenario changes too.
Hope that helps.