Thats the investment part you talking about and it works for those who have good initial investment and can buy large quantities of altcoins and bitcoins. For them it gets easier to catch the profits and its nothing but long term trading/holding strategy.

Different ways include earning the altcoin by all yourself by working for different bounty programs. Thats the prime destination for most of the altcoin hunters. You work for them in their signature campaign, social media and much more ways that they have. you get free tokens and that is how you earn them

Many people do follow only BTC based signature campaigns and earn BTC in small amounts but over the time it can be huge.