I presume that you don't yet fully understand how a buck converter works, otherwise you won't be suprised that the output voltage is not 5 V. To give a small hint, there's a point of discontinuous conduction (DCM) versus continuous conduction mode (CCM) operation. The simplidied duty cycle to output voltage translation is only valid in CCM, which isn't achieved for the given circuit parameters.
But instead of further studying literature you should primarly use the power of the simulation tool to look for the interesting details of circuit operation, which are presently ignored in your oscilloscope view. Which voltage waveform do you expect for the switching (source) node, how about transistor, diode and inductor current? Did you try to change gate drive frequency or duty cycle? What did you do during the "whole day"? Drinking coffee?
As a side remark, the presently implemented gate drive method can only work under very limited conditions, it's already touching the maximum Vgs limited. A real buck converter will usually implement some kind of level translation to drive the gate with a defined voltage between gate and source rather than gate and circuit ground.