Whenever people who typically aren't involved in the financial markets get invovled because prices keep rising for a particular asset class or a specific asset, it usually means a correction looms. This has been true about stocks, and it's true about pretty much any asset, including gold, silver, bonds, other commodities, real estate, etc.
Crypto is no different - whenever people pour into the crypto asset class en masse (especially those who traditionally aren't involved in finance, investing, or the financial markets), it usually means we're reaching a local peak, and a correction might be in order.
Of course, a correction doesn't mean things are through. Corrections can be healthy, and after corrections, we often see assets rise again above their pre-dip peaks.
Take a look at Google searches for Bitcoin below - one can see peaks and dips corresponding to rises and dips in the price of Bitcoin (and crypto generally). Interestingly, the spike in late 2007/early 2018 overshadows a lot of other data around it. As of this writing (October 2019), this pre-crypto correction peak is the highest point so far. However, any prudent investor who has studied market history would know that this might not be the case for long.
What is important to understand here is that whenever there's massive euphoria surrounding any financial asset, things aren't generally going to be good in the short-run and medium-run. If there's a ton of euphoria, media coverage, and both your Uber/Lyft driver and grandma want to get in on the action, it might mean the market is saturated with demand. If this is the case, prices for the particular asset might be inflated, and a correction might be in order. This isn't always the case, but it's the case most of the time.
Luckily, it's not hard to know when mass euphoria takes hold. If you're an aware person, you'll likely hear about the new asset craze at the office, at the bar, on the news, or online. Everyone knew about the Bitcoin craze in late 2017. If you want to take things a step further, however, a lot of data is available online that can provide useful proxy information - the Google Trends graph below is a basic example of this.
And now, given the rise of cyrptocurrencies and crypto assets to quasi-mainstream financial assets, we're dedicated to providing quality, relevant, and interesting material on cryptocurrencies and cryptoassets. Articles on Bitcoin, Ethereum, Ripple, Cardano, and many more cryptocurrencies and cryptoassets can be found on Pennies and Pounds - all that in addition to a plethora of information on what cryptoassets are, how the entire crypto industry came to be, blockchain/immutable ledger technology, mining, proof of work, proof of stake, and how to prudently invest in crypto if you are so inclined (based on your risk tolerance and ability to withstand the volatility that will come with a crypto portfolio).