Why do so many people tell me not to time the market?

You can actually judge for yourself when is a good entry point. Understanding the fundamentals and using technical analysis we can see whether the instrument is under priced or over priced.
We buy low, sell high, no one knows the exact bottom or top, but enough time analysing the markets will give you a a ball park figure.
Hence why education is the best investment.

A tale of two statistics

"1 out of 4 accidents result from using your phone while driving." Now, when you tell someone that, their normal reply would be to dismiss the statement and say: "It won't be me". This is know as "Overconfidence Effect", in which you feel that you are better than the average person when in fact, you are no better, or even worse than the average! Now on the other hand, the chances of winning the lottery is 1 in 13 million, but when you tell people that, their response is "I may be the lucky one: you never know". This is known as "Simulation heuristic"- in which people tend to determine the likelihood of an event based on how easy it is to picture the event mentally.

Two statements, two very different reponse

Obviously, the odds of you causing a car crashing while texting and driving is higher than that of you winning the lottery. But people tend to underestimate the former, and overestimate the latter. That my friend, is cognitive bias at work- why majority of the people buy high and sell low. Caught up in the moment of irrational exuberance, the crowd believes bull market run is here for good- prices will keep go up and up. Buy now or FOMO! The converse is true - the bear market seems to drag on forever as the atmosphere of fear and despair causes even the strongest bagholders to dump their holdings- it will keep dropping lower and lower! You can think of "timing the market" like choosing a job that has no basic pay, and is entirely commission based: this would causes you a lot of worry, and may not pay you as well due to your performance, and you will toss and turn in bed thinking about job stress. Of course, if you are great at it(Hint: most likely you are not), your upside will be unlimited, but the converse is also true(and most likely is the case): your downside is also unlimited too! On the other hand, "Time in the market" would then be a job that has a high basic pay, which makes it relatively "worry-free"- all you need to do is to show up! So, Time in the market(DCA-Dollar Cost Averaging) VS timing the market(Buy The Fking Dip: which one do you want? Worry, stress and headache "timing the market", or a fuss-free hands off approach in which you take the "time in the market" approach:)