Barely anyone does! We basically work in areas where the future value of money needs to be assessed. That isn't to say we're always right, but we use various different types of modelling to predict the current impact of future financial events. One example would be my area of specialization, pensions. You might ask the question of how much money would you need to invest today to receive £1 in a year? Assuming that you'll definitely live to receive it, it's simply a case of taking interest in to account and working backwards. If you change the time period to 25 years and the amount to £50,000, you need to predict what interest rates will do and assess the probability that you will still be alive. Expand this to a population of 50,000 pension scheme members with different ages, different amounts of pensions and different lifestyles, and you can see that it's not a simple problem. That's what I love about it.