People borrow money from friends & family, credit cards, or from their assets such as a home.

People lean on savings or take a tax hit and pull capital out of a 401k.

Smaller angel investors are a common avenue (someone that might put in $15k or $50k). They have very little in common with bigger VC investors, they're more like taking an investment from a friend or family member in terms of the actual relationship of dealing with them and their expectations.

Ideally, the absolute best way to non-VC fund, is by securing sales immediately. That is, to not start a business until you have your first customer. Now, that works for some things and not for others obviously, some businesses do not lend themselves easily to that manner of self-funding out of the gate.

If you're talking about a business that's already growing well but needs serious non-VC financing, that's very challenging. If you can demonstrate consistent growth over time and the ability to generate a profit, there are some options for debt financing with specialty financial firms. Traditional bank loans usually won't cut in that situation, that's usually a path if you're operating a franchise chain or convenience store, very traditional predictable businesses (ideally with some assets the bank can take if it all goes south).

The best book I've ever read detailing the struggle of self-financing a very successful company, is Shoe Dog by Phil Knight, in founding & building Nike. They were doubling sales every year for the first dozen years and nobody wanted to fund that growth, they were constantly on the edge of bankruptcy. They had no serious assets, no cash pile, no meaningful profit - all that growth was going right back into larger orders in a repeating cycle; so banks absolutely hated them and were aggressively reluctant to provide sales financing. It's fascinating to read what Knight had to go through to enable Nike to survive, how many times it almost went bankrupt despite meteoric growth.