If they are all different (i.e. you choose your numbers and make them different) then yes you’ll increase your odds. Same for a raffle, except you don’t need to worry about the numbers as each ticket is unique. But if everyone buys more raffle tickets with the same multiple, then your odds don’t change. If everyone buys more lotto tickets, everyone’s chances of winning increase (but also the odds of having to share the jackpot).

The issue is that the lane is physically dedicated to the USB controller. It’s not like all USB devices share a common pool of lanes. A USB port will connect to a USB controller, which is connected to a lane. If you have USB 2.0 controllers, as mentioned before you can have about 10 using a single lane and be fine, but for a 3.0 or 3.1 port the lane will be assigned to it and can’t be used for something else like an SSD or GPU, even if you only use it for a 2.0 device. Since we can expect many devices (eg mice, keyboards, webcams, printers, etc) still oy need 2.0, we don’t want to waste bandwidth and so we’ll have 2.0 ports, with a few 3.x ones for storage devices, high speed network adapters, external GPUs, etc.