will someone from apple please explain why it takes days to place all the photos from my Mac onto iCloud

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You're welcome.

The reason is that photos are fairly large. Those off my phone are 1.4MB (megabytes), those off my camera can be 3-4MB.

Most internet providers give us connections with fast download speeds but slow upload speeds. My connection is 10Mb/s (megabits per second, 8 bits in a byte) down, 1Mb/s up.

So assuming an ideal connection between my computer and the cloud, I can upload 1GB every 130 minutes. My library is currently 74GB, so that would translate to 6.5 days.

My connection is business service which means they guarantee those speeds. Consumer connections are often advertised with higher numbers, but those are "peak" meaning that you're not guaranteed those speeds, and typically share a line with many people in your neighborhood so your speeds will vary depending on how much your neighbors are using it. You can use speedtest.net to find out what speeds you are actually able to achieve.