It’s a bit more complicated than that. One way the shareholders support the company is that the company will hold sone percentage of its shares, which have a value as determined by the stock market. Amongst other things, the company can use those as colateral for loans which they may use to expand the company. The idea being that expansion will make the shares worth more, and increase income, so making the loans easier to pay off. Shareholders support the value of the shares by not selling them cheaply, This benefits the shareholders and the company, and if they think the company is doing well, they’ll tend to trade the shares at a higher price. If they think the company isn’t doing well, fir instance it’s not increasing its valuation, they’ll tend to trade at a lower price, further reducing the valuation, and making it harder for the company to raise funds through loans or share sales.

Basically the whole thing is held up by the common delusion that the share price is related to the performance of the company. It’s actually only related because everyone agrees it is.