After building a machine that can see the future, a young inventor and his friend use it to get rich, only to run afoul of gangsters.

If they can see ahead to make money, they can see ahead to avoid the mob. Movie over.

If your story is really of comedy genre then I find this 'cool'. If it will render around scientific elements more then this is 'not cool'.

Agreed with Adam and DPG.

Why not have the gangster take the future seeing machine and use it to get an edge? This gives the bad guy an advantage and levels out the playing field.
It would also be really cool if you establish that each time a different person uses the future seeing machine the future is slightly different as the person will act differently according to what they see. Adds to the theme that we're all in charge of our own future...