You want to invest them for higher returns in mutual funds. (wealthtrust.in)
Basically, you need to investigate whether you could earn more on the money by investing it for retirement than you could save on interest by paying off your student loans sooner. (money-rates.com)
And money NOT «spent» is then saved which means it is credit to someone who invests it for capital goods etc. thus it is again being spent, only not for consumption. (news-to-use.com)