Ah, but that was not your original question. Your original question was regarding a website that you own and use to buy BTC globally, in order to accumulate for yourself only, and whether in so doing whether you would be considered a Money Transmitter or operating a Money Service Business.

Now that you have addressed my response to you I can proceed to discuss. It is my understanding that you would not be considered a Money Service Business by FinCEN. MT requirements vary by state. Your activity would not be considered as MT activity in the State of Nevada where I am located.

Now if you act in a manner that crosses over into regulated activity, such as being given other peoples money to invest, or if you were a business entity,  or you had partners and so on....then you might be considered as running a business in ways that States may view as as MT. There might also may be SEC issues.

There are potential tax issues. If you have been using your accumulated BTC to buy and sell for yourself and you are making a profit, this then becomes subject to capital gains taxes and income tax.

There are laws regarding countries that we are not allowed to conduct business with. This might be an issue if you are purchasing BTC from a person in one of these countries.

Finally, large transactions get the attention of FinCEN. You must be careful that you are not just turning a blind eye to larger transactions that may look suspicious without gathering some information about the seller.

My answers free and intended to be general and should not be relied upon in these areas. You should always seek out paid legal counsel.     

I hope that helps:

George D. Greenberg, Esq.
www.attorneybitcoin.com