Many investors like altcoins because there is a profit on investing into it, most of the altcoin will follow btc bull run there are altcoin that rise very fast when the bull run begin that is why if we invest on dip and we get lucky from our investment and the price rise ten times higher then we will earn a lot from our small capital, bitcoin is so expensive now a days and it is very risky so many people prefer altcoin than btc.
Most people enter when Bitcoin is "bullish". I mean, that's what most "noobs" do. They get all excited once prices are going up, only to end up buying high and selling low. Like you've said, the right time to buy is when prices are low. It's just that most people are afraid of doing so because they think prices are going to decline even further. "Old timers" like myself know how the market works, so we will keep buying BTC no matter what.
Since the world hasn't completely moved away from cash (coins and paper money), I'd say it's still early to buy Bitcoin. The "fun" is just getting started...
