When you get your paycheck, why should you invest it at all? Why not just leave it in your savings account?
The major problem is interest rates. Normal banks give horrible interest rates in the neighborhood of well under .5%. With inflation at over 3% annually, your savings account is actually losing you 2.5% of your money each year! Of course, no one wants to lose money.
Lending Club helps you put that money to use by letting you lend the money you aren't using to someone else. People who need loans can grab money from you and will pay you back at a higher interest rate. The interest rates you can get range from 7% to just under 12%. For the money you have that's just sitting around, wouldn't you rather make a profit than a loss?
A simple compound interest calculator can easily demonstrate the differences. Investing $1,000 for 4 years at .5% will make you $20 in 4 years. That's almost nothing! But what if you invest at 7%? You'll make $310.80. That's over 15 times the gains from your savings account! Leaving your liquid money in a savings account is almost the same as just stuffing your money under your mattress.
Regardless of how you choose to invest, you can be strongly assured that lending your money to borrowers on Lending Club will net you much more money than your savings account. Don't waste the opportunity: invest.