I don't understand this, it costs more money, reveals your position, doesn't destroy the dart, costs a smoke and can be harder to aim. Why is this done?

A few weeks ago someone told me to lower my sens to 0.3 and 800 dpi. This was good and i did really well. But then one day i suddenly started playing really badly. The only thing i have done is try a bigger monitor and better mouse. After t...