Even the professionals have a hard time doing this profitably. If you are able to find a single rough crystal available to buy as rough, it is most likely because the professionals have passed on this stone for one reason or another.
On the other hand, if you are doing it for the joy of doing it and do not care that it is likely more expensive in the end than buying a finished diamond, then you can enjoy the process. If you are doing it to save money, that is HIGHLY unlikely.
Definitely not doing it to make a profit or all. Merely intrigued by a stone I saw listed for sale and curious/intrigued. But afterbseeing the price of he stone and he price of cutting it does seem that it is as cheap or cheaper to buy a cut diamond.