Just because you don't understand something doesn't mean they're lying.<p>If you are presented with 500 investment opportunities a year, and only have enough capital to fund 5 of them, you are going to pass on a lot of +PV opportunities.<p>Maybe they appear positive to you, but don't cross your hurdle rate.  Maybe they're overly correlated with other existing investments, so despite being positive, they're not ideal for your portfolio.  Maybe you want to avoid certain risks because you already have that risk in your portfolio.  Maybe you're running a double or triple bottom line company, and it works financially, but is inferior to another investment in another way.  Maybe it has more vol than you can fade.  Maybe it's fantastic, but you have another investment that's <i>really</i> fantastic.<p>There are almost countless reasons that a company could be great and a worthy investment, without being right for a particular investor at that moment.