What is the fine-grained topic of the following text: Actually, already a year ago there was talk of this possibility, which had not led to any final move and in fact it seems rather unlikely that Reddcoin can be purchased by Facebook and become the official tipping cryptocurrency, especially because its capitalisation is too small for a giant that has almost 2 billion users. Only return the topic.
Facebook's potential purchase of Reddcoin as its official tipping cryptocurrency.