What DRAM fab do you think has unsold capacity?
There isn't really any such thing as a DRAM fab. You can make DRAM at pretty much any of them, including the one in that guy's shed. There are some that specialize in DRAM. They all have unsold capacity, DRAM-specialist or not. The typical lead time is apparently about 18 months. The DRAM manufacturers (including in this story) keep saying they're "virtually" booked up for the next year. So you can call them up and schedule a run in a year, or 18 months, or maybe next week depending on what "virtually" means.
The OP is claiming that memory fabrication is "worse than OPEC" because nobody else can make memory. This is obviously not true. Intel is contemplating it. Many memory manufacturers have started up in the past. Most have gone bankrupt or been acquired. The limitation is that nobody wants to go completely nuts building new fabs that are very likely to be under utilized two, three or five years from now. So they're "only" increasing capacity at 20% per year. For context, world oil production capacity increases by a couple of percent a year and refining capacity, which is capital intensive like chip fabrication, by more like 0.5-1%.