The problem though, is that capital is also a shield against the reality of building a _business_. It saves you from talking to potential customers for a while. You can kid yourself that you're "working on the product", doing the fun stuff like writing code instead of the hard stuff like selling. Many, many tech entrepreneurs conflate "building a product" and "building a business". Making the most amazing product in the world is pointless if you can't market it. If you bootstrap or borrow then you have no choice but to get out there and find real, paying customers because otherwise you're screwed so much earlier. That changes your focus in a very good way.
It surprises me that investors put money into teams of hugely technical people who can't sell the amazing tech they can build and yet don't insist that they expand the team to bring in people who _can_ sell right at the start. It's often almost an afterthought, something that can happen later once the product is "finished". Raising capital _never_ means you won't need to do sales and marketing. Every successful business has to. The earlier the sales team is in place and having input into the business the better.