It's like talking to a brick wall.
Edit: I'm going to try to explain this by reiterating the context of our discussion and doing some simple math for you.
1) In the conversation, cabs specifically asked why you would cast Q on yourself or an ally.
2) BROseidon responded by saying you could use Nami's Q to get to lane or roam faster.
3) Thus, we are specifically talking about
whether it is useful to cast Nami's Q on yourself to roam or move down lane faster
.
4) Nami's base movement speed is 335. This means that in 1 second, she moves 335 units of distance.
5) Let's assume that Nami's Q has a 0.25 second cast time (which is pretty standard for most abilities). This means that when you cast Q, you lose (335 * 0.25) = 83.75 units of distance.
6) Nami's passive gives 40+(0.1*AP) movement speed for 1.5 seconds.
7) Thus, if you assume 20AP from Runes/Masteries/Items, casting Q on yourself will net 42*1.5 = 63 units of distance.
You would still LOSE 20 units of distance by Qing yourself as you head back to lane. You would need 150 AP in order to break even, which won't happen unless you are well into the game (at which point, you'd have boots and actually lose even MORE distance), or you're fed and snowballing hard, in which case it probably doesn't matter that you get back to lane a tenth of a second faster.
TL;DR, don't cast Q/W on yourself as Nami if you're trying to get somewhere quickly. Only E is worth because it has no cast time/animation lockout.