i couldn't watch past about 3 minutes as i almost died of boredom
In the first couple of minutes he asks the same question over and over in different ways, so I skipped to the six minute mark, where he was still asking the same damn question yet again (maybe there was something interesting in between). At that point I gave up. I expect most posts in this thread have said the same thing, or better, but in the appropriate number of words.
"Buy what you need" makes sense, of course, especially if you're a pro and know what you'll be doing with the lenses you buy, and I agree with what others have said along those lines. But if you take photos for fun, enjoy experimenting with different products, or are just learning your way around, it's also worth noting that you don't necessarily know what you want, let alone "need", and that using prime lenses makes you think differently about what you do. It can be an interesting exercise, for instance, to spend a day or two wandering around with a lens of a focal distance you think you don't want and see how doing so affects how you look at the world and whether it makes you encounter situations you find photogenic which had hitherto passed you by (28mm may = 28mm, but walking around all day with only a 28mm lens is not at all the same experience as walking around all day with a zoom lens set at 28mm, unless somehow immobilize the zoom mechanism). You may discover a new want/need you were completely unaware of.
And playing around with new toys like this needn't involve great expense, furtive receipt of heavy packages, etc. For one thing, responding to the urge to buy can be met with a rental - doesn't cost much, and you may not like the lens at all. Or - and I think this is much more fun - buy a mirrorless camera of some sort that has magnification and focus peaking (they pretty much all do that these days, regardless of price) and a few cheap adapters and try some old manual lenses, many of which are very inexpensive and really good (you have to figure out manual focusing, etc., but that's not necessarily a disadvantage...); and if you don't like them, you can probably sell them for at least as much as you paid for them.
Over the past few days I've been playing with a Canon 55 1.2, a Super Takkumar 55 1.8, a Minolta 50 1.4 and Helios 58mm f2, while awaiting a Jupiter 85mm f2 and Nikon 100 2.8 (the sin of focal length duplication...), all of which combined cost considerably less than, say, the new Sigma 50mm 1.4. There's more to life than satisfying "needs".