who writes these silly articles and why did you think it is worth sharing it here?
well it's impossible to know the reason for every Bitcoin payment, whereas PayPal literally do have a recorded reason for every transaction (although some unknown amount of that will be deliberate misreporting)
as a good estimate we could use the stats released by payment processors. since a great percentage of the merchants are actually using them, the stats is closer to reality and can give you a good comparison.
for example Bitpay claims to have processes more than $1 billion worth of payments for 2 years in a row (2017 and 2018).
Coinbase says they have surpassed $50 million on their merchant app launched in 2018.
i couldn't find anything from others.
my guess is that the total is somewhere around $3 to $4 billion per year at least. Paypal claims to have process $578 billion in 2018.
it is still great though for something so young, volatile and not yet mass adopted to reach these levels.