USB ->PS2 -> USB ->thumb drive -> WTF?

The adapters you have are pin compatible with each other and there are no electronics within them. They simply convert four pins one way, then back again. In essence, no converting is going on.

picture from ( link )

Both USB, and PS/2 are used for serial communication, and are very similar.. The largest difference is the PS/2 bandwidth is much slower.

Also see this section on the USB wikipedia article

Mice and keyboards are frequently fitted with USB connectors, but because most PC motherboards still retain PS/2 connectors for the keyboard and mouse as of 2007, they are often supplied with a small USB-to-PS/2 adaptor, allowing use with either USB or PS/2 interface. There is no logic inside these adaptors: they make use of the fact that such HIDs are equipped with controllers that are capable of serving both the USB and the PS/2 protocol, and automatically detect which type of port they are plugged into.plugged into.

PS/2 and USB are both 5v powered, but the protocols for each port are different. The adapters linked to are designed for devices which can detect what type of port they are connected to and adjust their protocol accordingly.