64 tick vs 128 tick doesn't matter, because even at 300fps, the game still only keyframes at 60. Anything over 60 is just frame doubled/tripled/quadrupled. Since the game is a 60 hz game [which means the animations are key framed at 60hz] you will NOT see a difference with 128 tickrate, as the server is now updating you at 128 times a second, but the game is only rendering at 60 frames per second, even if you're interpolating doubled frames.
This is the entire reason why valve uses a 64 tick rate, because even with a 144hz monitor, the game only keyframes at 60 fps. So 120hz, is just interpolating your 60fps twice, using doubled frames to reach the 120 frames per second, 144 hz is only 24 more frames, so it's interpolating 2.4 doubled frames per second. No actual extra data is contained within these extra frames since the game is keyframed, clocked and synced at 60fps.
There still to this day has never been a game that keyframes at 144hz, because if there was -- you'd NEED to hit 144 fps steady in order to not have frame skipping, this would mean the game would have considerably worse graphics in order to reach that target frame rate.
If the game didn't frame double, if you hit 144 fps, the game would be running at 2.4x speed, which means everyone would be moving around in turbo -- including the bomb timers. They'd say 5 seconds, and really explode in 2.1 seconds. The internal clock of CSGO is keyframed at 60fps, this is why anything BELOW 60fps looks choppy, it's because your skipping frames and anything higher than 60fps doesn't look any smoother without smooth motion monitor features, which actually create latency in your response time between drawing frames which slow down the monitor when it comes to drawing frames to interpolate those extra frames for that "smooth motion" look.
Any videos that attempt to prove this wrong are factually inaccurate and are most likely just ping discrepancies. For instance, while playing on a 64 tickrate server at 80ms vs playing on a 128 tick server at 5ms, the 128 tickrate server is going to have better registration and more accurate client state rewind -- it is however not because it's 128 tickrate, but actually because it's 5ms ping time. It can also be because of packetloss on yourside or the server side -- which again has nothing to do with the actual tickrate. You can verify this on Lan with a dedicated server, set it to 64 tickrate, then 128 tickrate, and it won't matter, registration will be exactly the same -- you can't however test it with online servers, since each server is going to have it's own trace route, which is going to net you variable pings and packet loss.
Since it would cost Valve around twice the money to run 128 tick rate servers, they know the science proves there isn't a difference, so why would they just waste all of that money for absolutely zero gain? Just to present the player with a placebo effect? They are a business, they are about making money -- not losing it. If it really made a difference, they would foot the bill, but it doesn't and they know it doesn't, which is why they don't. Oh and for the record, it's not just the servers bandwidth, it's the clients too -- for the server to update you 128 times a second, it would require the clients to send updates 128 times a second to the server, which doubles the bandwidth to the client as well.