All rallies do come to an end. The fact that we all don't know exactly what will cause this one to end is exactly part of the problem and 100% doesn't mean it won't happen. Usually some external shock spooks the market and a massive sell off happens.
So what could happen, any number of things. An obvious near term issue might be inflation increases dramatically in the US (on account of the oil shock), causing interest rates to increase - maybe dramatically - , which causes the stock market to retract. Also, the housing market is pretty much toast at the moment and an increase in interest rates might finish it off too causing a contraction there. So many ways things can break.
But honestly, I'll tell you after it happens and it will happen. Having lived through a few of these now when everyone tells you it's a sure thing and prices go up for ever you get an inkling you are near the pop.
So what could happen, any number of things. An obvious near term issue might be inflation increases dramatically in the US (on account of the oil shock), causing interest rates to increase - maybe dramatically - , which causes the stock market to retract. Also, the housing market is pretty much toast at the moment and an increase in interest rates might finish it off too causing a contraction there. So many ways things can break.
But honestly, I'll tell you after it happens and it will happen. Having lived through a few of these now when everyone tells you it's a sure thing and prices go up for ever you get an inkling you are near the pop.