Choosing to do the harder thing may not always be productive or practical. If I think it will take me 3 years of research to (maybe) solve a problem and bring a product to market, and I know another problem I can probably solve in 6 months with the same potential financial reward, which one should I choose?
Start the three-month project. In a year, there will be ten different companies competing over the shorter-term project, and you'll be ahead of everyone on the hard problem.
