Buck Converters Decreasing Current Consumption

Yes! P=U*I. Increase voltage and the current drops and vice versa. It's the entire point of having a switcher instead of linear supply.

I read that a buck converter steps down voltage by increasing current.

This means that the output current is higher than the input current.

What you are seeing is that the input current depends on the input voltage. This is true because of, as others have mentioned, conservation of energy. Because of conservation of energy, we can define the following rule for a buck (or other switching) converter:

$$V_{in}I_{in} = \frac{1}{\eta}V_{out}I_{out}$$.

Here, \$\eta\$ is an efficiency factor to account for power lost in the converter itself. It does vary slightly when the other parameters are changed, but it's typically between 0.85 and 0.95 for a well-designed buck converter.

So you can see that if the output voltage and current stay the same, but you increase \$V_{in}\$, \$I_{in}\$ will decrease.

I read that a buck converter steps down voltage by increasing current. But what I got was another way around.

Your logic is incorrect.

1) You step down the voltage by increasing the current.

2) Therefore, the more you step down the voltage, the more you can increase the current.

3) The more you can increase the current, the less input current you need for the same output current.

4) Therefore, the more you can step down the voltage, the less current you need.

5) Thus the higher the input voltage, the lower the input current.