Re: interesting article: Pay-to-use blockchains will never achieve mass adoption
With such argument, i would point out it's free to download Bitcoin wallet software.
sure you can download a zillion different bitcoin wallets maybe that's free you can make as many bitcoin addresses as you want but you can't really DO anything with it without paying fees. and those little wallet softwares you download onto your phone aren't full clients. to actually download bitcoin core and keep it updated you are going to pay. pay in computer hardware and internet connection and then when you actually want to do a transaction you're going to pay a fee in bitcoin too. don't forget all the time it costs you to set up and maintain your copy of the blockchain too because no one is paying you for that...
It's true creating Bitcoin transaction always cost some fee, while bank (or different financial service) charge fee only on some occasion (e.g. transfer to different bank account). But most people would just SPV wallet where they never have to think about download and store blockchain data.
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And PayPal usually charge tx fee.
they never charged me any fee for buying things on ebay.I don't use eBay, but isn't it because either eBay used to be owned by Paypal or fee is paid by seller? Anyway, generally Paypal generally charge fee which can be seen at https://www.paypal.com/nz/webapps/mpp/paypal-fees.
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Most people who use Facebook only use it for communication purpose though.
which is totally free.Quote
So IMO comparing total Facebook and Bitcoin user isn't good comparison. For example, how many Facebook user ever use Facebook Marketplace (where actual money transfer usually happen outside Facebook system)?
apparently facebook marketplace is also free. free to sell stuff on. you don't pay a fee to facebook for using it. apparently. 
That's true. But my point is even being free doesn't always mean existing Facebook user going to use it. Otherwise, we'd see Facebook Marketplace in domination.