I do not know whether it is possible to leave the bitcoin in the real state and at the same time that they worked on their increase. But in reality, you can find a company to invest in bitcoin bitcoin up getting interest.
No its not possible i think if some one can spend bitcoin in real estate because it is a real life investement and bitcoin can be used as investement only in the online world.And i dont trust these online investement companies accepting bitcoins and there is huge risk involved in that investement.
Don't ever invest in any sites which is not a trusted sites. But not all online sites are scams because you can find many good and reliable gambling sites to invest our coins in their bankroll and can grow our money. You can just keep bitcoins for a longer term then surely you will make good returns on your investment and no need of any other investments.