Regardless of where volume is coming from, it will always be temporary. Prices can only be lifted, or suppressed, for so long. Either prices drop to reflect earnings/data or they are predictive of better data ahead.

However, given where interest rates are, its not all that surprising to see stocks at these high of valuations, especially if consensus believes rates are on hold for the foreseeable future. Just look at how much margin debt investors have taken out to buy stocks over the last few years (myself included).

I agree the market is likely overvalued. I've been decreasing exposure with every leg up. I'm not ready to switch from stocks altogether altogether though. While data has been muted, leading and coincident indicators have yet to trend together into negative territory.

In any case, it's a process of time and not so much a 'burst'. Now is probably a good time to explore other markets or assets that haven't run up so high in recent months/years. Perhaps gold/silver or foreign markets of less indebted nations?