Keep in mind that when 10nm was in planning, EUV light sources looked very exotic relative to current tech, and even though we can see in hindsight that the tech works it is still expensive to operate -- TSMC's wafer costs increased 2x-3x for EUV nodes. If I was running Intel and my engineers told me that they thought they could extend the runway for DUV lithography for a node or two without sacrificing performance or yields, I'd take that bet in a heartbeat. Continuing to commit resources to 10nm DUV for years after it didn't pan out and competitors moved on to smaller nodes just reeks of sunk-cost fallacy, though.