It's pretty cheap, commonly used in one-time plastic items, and is the most common 3D printing plastic.
But also, you can make polypropylene and polyethylene pretty easily from methane (which can be from biological sources or synthesized from electrolyzed hydrogen and CO2) via methanol-to-olefins processes, common in China.
But you're missing the point. We can synthesize literally anything you can make from oil using hydrogen, direct air captured CO2, and the Fischer-Tropsch process. It's a complete replacement for crude oil. It's just more expensive than getting it from the ground.
Are folks just not aware of this, so they think people who say you can "make plastic out of CO2 and water" are talking hand-wavy nonsense?
The process is used commercially today in Qatar, Malaysia, and South Africa plus has had pilot plants in the US. But many of these US pilot plant efforts stopped when the price of oil cratered. So again, we absolutely do have alternatives to crude oil, it's just a function of economics.
In the 00s, we pursued biofuels (ethanol, biodiesel, bioplastics, etc… which has problems but does still replace some uses of oil) and on-shore wind aggressively.
In the 2010s, we developed battery electric vehicles, grid storage, solar, and off-shore wind.
I suspect this decade we’ll see hydrogen steel and ammonia production, battery electric flight, and chemical carbon capture. Another decade of this and expensive methods of oil extraction just aren’t very feasible, so if the price spikes, people will just switch to alternatives faster or even start synthesizing carbon neutral hydrocarbons (ie via electrolyzed hydrogen, direct air CO2 capture, and Fischer-Tropsch).