a windfall tax on profits means that...gas prices will stay higher in the future than they would have been without the taxWhy?
theory ... tells us that excess profits attract the competition that wipes them out... and do so by lowering the prices of those things which were in short supply. Which is, I think, exactly what we all want to happen, no? Let's make gas cheap again! So confiscating those extra profits will mean that first, no one making them has the money left to look for more and, secondly, no one is going to dive into the industry if they think that they won't be allowed to keep the profits they might make.