I actually arrived on the scene right in the midst of one of these spam attacks in 2016 - back then I actually thought Bitcoin was that popular, but even starting out I quickly saw that most of these txs had to be artificially introduced - just the volume of similar sized amounts, dust txs that can't possibly have been actual transfers of value (BTC wasn't even $1k at the time).
there has been many spam attacks against bitcoin, some were more obvious than others and it has been happening for at least 3 years now, incidentally near the same time scaling debate started back in mid 2015.
the oldest one that i know of is the following one which led to some academic papers being written!
a little bit of history!
the oldest massive scale spam attack that i can remember was called "stress test" back in Aug and Sep 2015 where they started sending transaction with 0.0001BTC and 0.0001BTC fixed fee. then to make matters worse they started releasing the private keys of the addresses involved. soon there were hundreds of people with access to these keys and hundreds of transactions spending the same outputs.
https://bitcointalksearch.org/user/coinwalleteu-553487
interestingly enough, this method of spam attack is still being used. 1BoatSLRHtKNngkdXEeobR76b53LETtpyT is a well known bitcoin address used in vanitygen with a publicly known private key.
the oldest massive scale spam attack that i can remember was called "stress test" back in Aug and Sep 2015 where they started sending transaction with 0.0001BTC and 0.0001BTC fixed fee. then to make matters worse they started releasing the private keys of the addresses involved. soon there were hundreds of people with access to these keys and hundreds of transactions spending the same outputs.
https://bitcointalksearch.org/user/coinwalleteu-553487
interestingly enough, this method of spam attack is still being used. 1BoatSLRHtKNngkdXEeobR76b53LETtpyT is a well known bitcoin address used in vanitygen with a publicly known private key.
