for all hobbyists that don't earn from photography... how do you convince yourself about what is a "need"?
technically everything is a want.
unless you will convulse and have seizures when your camera is taken from you
From a hobbyist:
1. I identify what I like (or "want") to shoot (not the gear I like or I want to get
)
2. Then based on no. 1, I'll try to find the gears I NEED.
As for my case: I like to shoot candid, street, event, and portrait.
That translates into: 1 crop body (Canon 60D), 1 UWA (Tamron 10-24), 2 primes (Canon 28mm 1.8 & 85mm 1.8), and 1 telezoom (Canon 70-200 2.8 IS mk1). All bought second hand except the body.
I don't have any speedlight (at least for now), because - well you don't really use flash for street (prefer to stay discreet), and most likely won't be allowed to use one during events (think something like night music gig, small concert, etc). And so far my primes handles low light conditions well.
Of course I won't be able to achieve something like this ->
http://pixelcurse.com/wp-content/uploads/2011/02/jump_23.jpg but oh well..
(* Attached picture credit: Jump! by Lénárt Gábor)
My 2 cents.