What's to stop you stealing anything?

Cops, usually

this wouldn't be your normal case of pirating a tv show. You use one of these logos and end up becoming a large successful company you will be paying when you get sued.

What stops you from calling your company Coca-Cola and using their logo?

A DMCA takedown notice, probably.

You get the illustrator files if you buy the logo, otherwise you only have a thumbnail.

These thumbnails are clean enough to be loaded into Illustrator and recaptured using the vectorize tool. Not sure about Inkscape.

How much would people pay for such tracing do you think?

Does it matter? Vectorize the thumbnail all you want, you still don't own the logo.

Probably not enough to cover the eventual copyright infringement lawsuits.

Morals?

I guess if you enjoy being sued for $X amount of dollars then nothing is stopping you.