Ur point is correct, as people investing money in BTC actually does not know the underlying blockchain technology. Most of people are in state of FOMO( fear of missing out) so they are investing and now institution money coming in like CME or CBOE this year and next year, institutional money is trading and making it high volatile. However as a true believer in technology and long term it is worth. As always 90 % people lose in trading and long term investors outperform them in all way.
About the control it is decentralised but not very decentralised as 20-30 big players are involved heavily and as long as their pocket is being filled they will keep the network stable but thing like Bitcoin Cash they will try to switch sides as miner loves only money at the end of the day. So it is still very early how far the BTC goes. But in overall Science behind is innovative and lot of project are awsome in this field.