Only high-growth, high-margin businesses can get 7x+ earnings.
Creating a sufficient level of growth to garner 7x valuation is very tough to do bootstrapped.
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EDIT: The only reason anyone gets a 10x etc valuation is because they're doubling+ year-over-year, and very likely they'll be 3x bigger in 18 months.
So basically, that's a 3-4x valuation...of your probable revenue in a year and a half.