Investment plans for young entrepreneurs

So today at work, we had an interesting discussion specifically to invest 401k and long term. A strategy that one of my finance professors had spoken to me about the surface to be one of my colleagues. He has suggested that for younger investors who want to invest long term, the best way is to put 100% into something that really believe in race and out.

The idea is that for most large enterprises and companies of birds, the overall trend is upward, but every day you can expect large fluctuations, which does not correspond to any stock index.

Take for example the S & P 500 historical returns. Looking back, here are the breakdowns by length of investment and simple annual statement on investment (ROI):