Buy or develop your own time machine and go back to 2008 and mine BTC on the computer at your mothers house in the basement
here everyone to make money and want to become rich . but that person became rich who have big Network through sites and program . if you want became rich then you don't have need to make time machine and no need to go in past . just make your own site service .
I do not think it necessary to make a time machine because it could not do the things that are irrational and impossible to happen,
it might be more rational if you could tell the future maybe you can become rich with the surplus?