If you don't have good enough pot odds
you will loose money anyway, so you can take that risk but with good enough pot odds
. Sa basically you can limp into pots with many limpers, or limp on bb, or sb. And this is how you can take this additional risk (playing hands out of range). Playing otherwise you will lose, because you take risky bet with not enough reward.
Lets say you have unsuited 5 & 2. Only chance of winning is making straight, but lets say you make 5,4,3,2,1. Other guy can have 6 & 5 and you will lose, so you have small chance of making straight, which will be not nuts! So there are hands that you shouldn't play even with great pot odds like 1:4, or even more.
Generally reasoning behind this play is - i will lose many times (with suited connectors or A,X (S); but i will make a lot of money if i will flop monster/monster draw and i will draw to it wuth succes). Its agressive play with tough decisions in case of not flopping nuts, so its hard for beginners.
Maybe you should reason like this - at beginning play is almost free so its better to have solid game and risk later. But its your choice ofc.