[portent]

Here you are confusing the secondary market for shares (an existing shareholder selling to someone else) with the primary market (new issuance of shares).

The primary market for shares absolutely benefits companies by giving them large amounts of cash now, in return for a claim on future earnings. This can allow a company to create more value than it otherwise would be able to do.

The secondary market is mainly a benefit to shareholders, not companies; but without a liquid secondary market, there would be fewer people willing to invest in the primary market.