It's not enough to simply have
part of the supply chain. A crucial piece is the one which happens at the foundries. If you don't have that, it doesn't matter how much other R&D you do, you still cannot make leading-edge chips.
Just look how hard it's been for Intel to regain leadership. Do you seriously think that if China locked up access to TSMC's new nodes and Intel had to cease development of new nodes, that we could just turn the key and rev back up to a leadership position overnight? I see no evidence that would be possible, or else why didn't Intel have 18A ready last year? If they had the equipment needed for 20A, they should've been able to do 18A product, no? So, likely it wasn't a matter of simply not having the equipment.
Node development takes a lot of time, resources, and expertise! Consider the > 30k wafers they've gone through on high-NA, which isn't yet even production-ready!