Bitcoin (CRYPTO: BTC) crossed the $67,000 level for the first time since 2021 on Monday, adding another leg to the unrelenting rally over the last six months. CNBC’s Jim Cramer believes he knows what’s pushing the world’s largest cryptocurrency higher. What To Know: Bitcoin has been on a tear as of late, surging back towards the all-time highs it set in November 2021. Most have attributed the rally to increased demand stemming from recently approved spot Bitcoin ETFs, as well as anticipation of April’s halving event, but Cramer thinks something else is driving the buying. “I first thought the …