so you are saying you are buying a coin with 7 full nodes? i do not think you really understand blockchain ....
Do you mean that Qtum has just 7 nodes? Its not looks like decentralized... Even EOS has 21 nodes and people guess that is centralized while others blockchains have more than 100+ nodes...
Qtum is one of the coin with huge number of full nodes, Current count as shown on their website is around 2000, During full node competition it was peaking at 5000+ nodes. Qtum is one of the most decentralized blockhain.