I'd bet on services businesses being substantially more numerous. There are probably tens of thousands of consulting firms in the US. Most of them produce bespoke software for businesses at five/six figures an engagement.
There are also lots of non-software consulting firms of various kinds; I'm part of one, and we do grant writing for nonprofit and public agencies (see www.seliger.com if you're curious). Small non-software consulting firms you've never heard of probably outnumbered software consulting firms.
Still, one thing I'll point out, which The Millionaire Next Door points out, is that it helps to play good offense (i.e. make a lot of money) and good defense (i.e. save a lot). Many of the high-income people I know are bad at the second. That's the force counteracting gravity for many people.
There are also lots of non-software consulting firms of various kinds; I'm part of one, and we do grant writing for nonprofit and public agencies (see www.seliger.com if you're curious). Small non-software consulting firms you've never heard of probably outnumbered software consulting firms.
Still, one thing I'll point out, which The Millionaire Next Door points out, is that it helps to play good offense (i.e. make a lot of money) and good defense (i.e. save a lot). Many of the high-income people I know are bad at the second. That's the force counteracting gravity for many people.