In a capitalist society, to a rounding error, most people work out of necessity - to house, clothe, and feed their families. This creates an inherently unequal relationship between capital and labour which is exploited to accrue wealth in the hands of a very few people.

This is literal theft from the working class of the fruits of their labours.

Billionaires become billionaires because of preferential treatment by governments, not out of any kind of merit. There are lots of better things the world could have had, Linux and the software commons would be much much much better if Microsoft hadn't hired all the best software engineers to make proprietary software and if the federal government hadn't coddled it and overlooked its monopolistic practices. The Internet would be a much better place without the likes of Google and Microsoft throwing their weight around.

It's perfectly accurate to say that billionaires steal from the public, it's just that what's being stolen isn't easily quantifiable because it's effectively 'potential'. Think of the constant enshittification of everything and you get a sense for what's being stolen.