Knowing your shit and having liquid cash is key to those opportunities. My play portfolio made a 10x return after the financial crisis because of knowing key sectors and having cash.
Likewise, I had a nice bitcoin hit that could have been a 1000x play, but to be honest I got out to buy a car, which in retrospect was a very dumb decision!
I cashed out a bunch of bitcoin for what I thought was going to be a near peak price at the time, $800. Fortunately, I never agree with myself completely, so I saved a few for the long run. Thinking back, I can't really say I would do anything differently with the information I had at the time.
This isn't investment advice. I think the idea is that you'll have some investments that yield 1000x and some that yield 0x so you'll average out to something that's better than the market, but not 1000x.
I'll admit I'm surprised by Bitcoin, I actively avoided it thinking it would crash long before now. But I wouldn't treat the past five years as anything remotely "normal". We're in one of the longest bull markets the US has ever seen and there are a lot of macro forces that will eventually end it, e.g. boomer retirement, student loan debt overhang, pension obligations. I was just reading some of Dalio's daily observations on some of this, they're quite good.
Things like pharmaceuticals with ok pipelines, good companies in shitty sectors (say a company like Costco in retail), health insurers and companies like McDonald's that do well when the rest of the world does not. Think about smaller players who benefit from net neutrality going away.
You should have a running list of good companies and invest as you see corrections or downturns.