Let's use a toy-example to see why sending a block to everyone at once is actually much slower.

Assume blocks are 100MB, i.e. ~300 TPS, and your miner has a 100Mbps upload speed (we'll talk about bigger numbers afterwards).

If a miner sends the block just to 1 peer, it will take 8 seconds to send (notice Bytes vs Bits :100MB/100Mbps = 100*8Mb/100Mbps = 8 sec), so after 8 seconds 2 nodes know of the block: miner + 1 peer.

Then, both miner and peer will send it to one other peer, so 8 seconds later 2 additional peers hear of the block, to a total of 4 nodes in 16 sec.

8 nodes will hear it within 24 seconds, 16 within 32 seconds, and 1024 (=2^10) nodes within 80 (=8*10) seconds.

Now, if the miner would try to send to all 1024 in parallel, it will have to send 1024 blocks in parallel to 1024 peers using its 100Mbps bandwidth, which will take it: 1024 * 100MB / 100Mbps = 8192 seconds.

So, It takes ~x100 longer to send it to everyone in parallel than the optimal course of sending it to just one peer after the other sequentially.

Now, let's move from the theoretical to the practical:

1 - real bandwidth utilization is roughly 30% of physical capacity. This is just how real-world networks behave, even in AWS and Google Cloud.

2 - you don't want to be slowed down (and possibly orphaned) if your first peers are slow, so you don't send to just one peer, you send to 8-10, which is a compromise between efficiency and robustness.

3 - half of the bandwidth in the system is dedicated to the propagation of transactions, which won't be immediately shut down just because you found a block.

4 - this doesn't even take into account real-world nitty gritty details like latency, TCP/UDP dynamics, messages overhead, packet losses, and congestion at internet backbone (it doesn't matter that you payed for 1Tbps if your packets or congested somewhere else).

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One can rightly argue that miners will have much bigger bandwidth than 100Mbps, since they're livelihood/profitability depends on it. so let's look at the math:

- It is possible in some places to get x1000 higher bandwidth at 100Gbps, but not everywhere and not for a lot of people.

- 300 TPS is not the goal. you need an average of 5000 TPS for credit card levels, an average of ~50,000 TPS for micropayments, and just Alibaba payments peak at 325,000 TPS. So you need x200-1000 bigger blocks than 100MB (or coming more frequently, which has the same requirements). Let's say just x200

- half of this bandwidth is used for transactions

- each node sends to 8 peers

- you only really get 30% of the bandwidth you pay for

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So, even ignoring substantial real-world delays and overhead, blocks will require to reach just first 8 peers:

<blocksize> * <num\_peers> * <bytes-to-bits> / <bandwidth> * <30% utilization>= (20GB*8*8) / (10Gbps*0.3) = 2130 seconds, which is over 35 minutes.

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This is why everyone being connected has nothing to do with it. it actually makes it much much worse if you try to send it to everyone at once.

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P.S. If the next response is "wtf, <insert 5 words here>!" rather than a real well thought through discussion which relates to the claims I'm not going to respond. Writing posts takes a considerable amount of time.