If I pay a plumber to fix a pipe in my house, and the value of my house is assessed now to be higher, I neither owe the plumber any more than the agreed rate for the pipe fix service nor equity in the house. If I owned 100% (or 20% per your company example) before, then I still own 100%. If the plumber was already a shareholder, then he will reap the additional reward.

Any asset value can grow or shrink thanks to effects from people, such as paid services, but I don't lose equity on property/companies I don't own if I vandalize them, just like I don't gain equity when I raise their value somehow.

Employees of a company are just contracted service providers with longer duration contracts, and of the company is public, they are free to buy some of that risk and gain or lose more when the company does so. 20% of $100B is $20B, so there is no need for a debate, math has our back.