Some did:
Sony: started in 1945 as an electronics repair shop. Built-in audience
Microsoft: in 1975, MITS requested Bill Gates and Paul Allen sell their BASIC interpreter for the Altair before it was even written
Amazon: started in 1994. Everyone buys books, they just needed people to do it online
Intel, Apple, and Google were much riskier. Google wanted to sell its search technology to giants like Yahoo, but Yahoo refused. Apple built products no one knew they needed, but now we can't live without (hackable PC). They continue this today (iPod, iPhone, iPad, etc.).