[marcus_holmes]

>...but then again I haven't seen a tech unicorn that hasn't been funded by investors.

Partly because if you're not in the target market for a bootstrapping business, you probably won't have heard of them. It's a waste of money, time and energy making a big noise about your business if you're not chasing investment.

Partly because the desired exit for bootstrapped businesses is (usually) a trade sale. You can't trade-sale a unicorn-sized business because finding a buyer that big is difficult/impossible. Bootstrapped businesses tend to sell before they get that big, while they're still showing huge growth, to make sure they have enough potential buyers.

Partly because valuations of bootstrapped private companies are weird. With no VC driving valuation growth, and no stock sales, how much is a private company actually worth? Valuing one is tricky, and a lot less important than for an investment-driven business.