Krishna draws a clear line. Those who worship the devas receive the fruits they seek, yes. But those fruits have an end. They are temporary. The worshipers of devas reach the devas. The devotees of Krishna reach Krishna.
The word 'alpamedhasam' is not harsh. It describes someone who thinks only of the immediate reward, not the larger picture. Like a child who works only for today's sweet versus another who works toward a goal that will sustain them for life. Both receive something. But the nature of what they receive differs vastly.
This shloka does not disparage any deity or any devotee's practice. It simply describes the difference between limited and unlimited destinations — between fruits that expire and a refuge that does not.