Well in terms of timing, perhaps having a large hashrate just before a boom will be 'lucky', so maybe we will see ROI. I admit we'd have to be lucky, but it is still a possibility.
A boom in what? A BTC valuation boom isnt going to help you generate a BTC denominated profit. Au contraire, it will only add fuel to the already explosive network growth (and of course, helps BTC holders like me).