The issue is that refineries are expensive and take a long time to build/reopen/expand. This means that any big investment you make is going to take a while to earn back it's costs.

Energy companies see the writing on the wall for the oil market, and that even if right now we've got a little rise in demand (vs the pandemic) we're likely looking at demand being in a long-term death spiral.

Many parts of the world and many US states are looking to outright ban new sales of fossil fuel vehicles within 10-15 years, and even in places that don't it's likely there will be an ever-increasing share of the market eaten up by electric vehicles. Elsewhere, there's a concerted push to switch away from oil/gas for household use and electric generation.

Even if you've got expensive gas right now, when they believe in 5 years they're going to be needing to close refineries/cut capacity, and will be in that downward spiral for decades, there's no reason to want to expand now.