13.5BTC is really a huge amount nowadays to but you made a good decision maybe it has been a long time that I have not heard or seen that such a huge amount of money is being traded from users here in forum or any other guy that I know which unfortunately deal only on deal under 1 bitcoin.
If you want my suggestion then I would suggest to split the budget and try the altcoin too, it maybe sounds unfamiliar to you but the altcoins is a huge market and with a high potential to earn a good profit but also to loose as there are many many project that are pretty good that have added many features that bitcoin does not have.