> since the companies issue their own stock, so they don't need to buy anything to sell it,

Public companies diluting shareholders generally causes people to flee for safer investments.

A company is not a person. It doesn't always own 100% of itself.

Selling treasury stock has the same effect of diluting external shareholders, so the safety thing is the same - it depends on their assessment of the underlying reality.

And the person doesn't own himself, he is himself