Ok that's fair. Can they made by oil byproducts only or can it be eventually synthesised from CO2?

You can synthesise basically anything from CO2 and hydrogen. You can get syn-crude which can the be treated the same as regular crude. If we had "unlimited" electricity we could make basically anything from air and water.

I’d just like to support this by saying that this is what plants and micro-organisms do. They make many of our chemicals from air and water.

Yes, it's just cheaper to pump it out of the ground in a nearly ready-made state.