Will 3 expensive lens be enough to cover all of your needs? explain. I'm genuinely curious to hear
No. The cost of the lenses is irrelevant to me.
I'm sure it's not completely irrelevant - a relatively minor factor in your lens purchases perhaps.
There are lenses that sell for hundreds of thousands. Each of us has a limit on how much we can spend, and quite often a considerably lower limit on how much a particular improvement is worth to us.
If two lenses were somehow the same in EVERY measurable and subjective way except price & weight, would you pay £1000 more for the lighter lens? If the weight difference was dramatic enough you might, after all a lens you can't move is of little use, but to save only 1oz it's somewhat unlikely.
Price is a big factor in what I will buy, but I will sometimes splash out over my normal limits to gain an ability my previous lenses don't have. Lenses under £20 might be brought on an impulse (and sometimes regretted 20 minutes later).