Blockstream developer and Hashcash creator Adam Back has said he would pay $100 Bitcoin transaction fees, and “bets” users would too.

In a Twitter post, Back responded to a similar assumption by ex-Bitcoin Foundation Executive Director Bruce Fenton, who considered users “would be willing” to pay $20 fees.

i bet they'd pay $100/tx for digital gold, and mid-sized international remittance, I would. still be really good if fees were much lower. https://t.co/YDn4cRr8rw — Adam Back (@adam3us) June 7, 2017

Both added that lower fees would be “good” and “preferable” respectively.

The comments come amid continued broad frustration among Bitcoin users regarding high fees and associated long transaction processing times.

Coinbase has come in for specific criticism, with multiple reports of higher fees for using the wallet and exchange service compared to others on the market, often with noticeable advantages.

Back’s comments produced mixed reactions.

While some said $100 per transaction would not be accepted by users of a decentralized apparatus, entrepreneur Alan Silbert appeared to agree, responding that the security element of Bitcoin would see investors pay the price for peace of mind.

Not saying I want $100 txs, but you are wrong. People will pay for the security in Bitcoin if using as store of value. — Alan Silbert (@alansilbert) June 7, 2017

Silbert added too that he “did not want to see” such high fees.

Elsewhere, the vat of unprocessed Bitcoin transactions known as the mempool has been steadily decreasing in size so far this month, coming down from highs at the end of May.