Technically yes, the working class can become capitalists by just saving their money. Practically, I don’t think I need to explain why that’s a dishonest and rude suggestion, at best. Just because anyone can become a shareholder in a company that squeezes its employees dry for profit doesn’t mean that that company isn’t a weapon in the class war.
From Wikipedia: Federal Reserve data indicates that as of Q4 2021, the top 1% of households in the United States held 32.3% of the country's wealth, while the bottom 50% held 2.6%.