Why do some miners only confirm their own transaction?

[Zyger]

Every so often I see that some miners only confirm their own transaction, instead of confirming as many as possible, meaning they'd lose out on the extra BTC from the fees.

Here's an example from block 646643: https://mempool.space/block/00000000000000000003df4d47029e345e693663c0c28ad6aa44523d5f5f821f

Does anyone know why they do this? Are they just being lazy and don't want to hash the entire block or something?

Thanks.

[actmyname]

One possible reason would actually be malice rather than laziness. If one wants to "spam attack" a blockchain, they can continually mine empty blocks with only the coinbase transaction to let the mempool fill up and raise the fee that the average transaction requires with a large number of transactions flooding the pool in conjunction.

You can effectively make the network operate on a higher difficulty if you have these malicious miners present.

[OgNasty]

The short answer is that every millisecond counts if your operation is big enough.

Source: https://bitcoinmagazine.com/articles/why-do-some-bitcoin-mining-pools-mine-empty-blocks-1468337739

Why are there empty blocks?
When a mining pool receives a new block from a competitor, it needs to perform a few actions: download the full block, validate its transactions and define a new block to mine on. During this – albeit short -interval, so as not to waste hashing power, they start mining a new block. Only the coinbase transaction is included, so the previous block does not invalidate theirs with a duplicate transaction.

This validationless mining (or SPV mining) phenomenon can be seen on the Kaiko blockchain page, with empty blocks being mined just after a normal block, when the mempool is far from empty.

[tranthidung]

Please give me a post to promote my analyses on empty blocks, top-10 mining pools, zero-fee transactions.

• BTC empty blocks (2009 - 5 May 2020): miners, size, daily, monthly,yearly stats
• Top-10 mining pools on bitcoin network over years (2009 - May 2020)
• Zero fee for bitcoin transaction [Historical data] (pooya87 post presents full and correct details)

[Steamtyme]

A poorly designed back end for their private pool can also be a reason. This shit goes way beyond my understanding of mining and pool ops, but Kano Pool has the ability to never mine an empty block, assuming there are transactions available. He often points to the failure or lack of concern when larger pools mine empty blocks when there are loads of transactions available to benefit miners.

slush generates empty blocks.
EMPTY blocks are not necessary and are a sign that the pool is slow and coded badly.
slush block 645736 EMPTY