It can’t really harm the decentralization because bitcoin will remain decentralized but people should just realize that it’s better to buy and hold bitcoin on their own. Transact using bitcoin with other individuals and not companies. The companies will just stay benefiting from the demand bitcoin is getting but this will not mean they can completely kill bitcoin’s decentralized network.
I agree with the bolded. Decentralization has to do with mining—the way Bitcoin is produced and not with the entities holding it.
"Transact using Bitcoin with other individuals and not companies."
This wouldn't make any difference. Whether small holders transact with companies or other small holders won't make any difference, because the companies have the financial clout to keep acquiring bitcoins irrespective of whether you deal with them or not. As I said earlier, the big players holding a lot of bitcoins has no impact on its decentralization.