This is really the biggest issue for Disney. Even they did build one coaster that was intense enough to interest big coaster enthusiasts, one just isn't enough. Most of them aren't going to go to ride just one attraction when there are numerous other parks that offer many, so it likely wouldn't be a massive draw for that demographic.
They're really too far behind to catch up to other parks for that demographic, unless they wanted to solely invest in monster coasters for several new attractions in multiple parks. But that wouldn't do much to help capacity for their core audience, while attracting more guests solely for those coasters, so it would potentially cause more problems than it would solve.
Their best bet if they really wanted that market would be to build a 5th gate that mainly revolved around big coasters, but I don't think that would be worth the investment for Disney.