While google is a cloud competitor, azure remains a larger competitor. Regardless, AWS is positioned to hold the large majority of the cloud market for a while. Not to say that any of this is unhealthy.
That graph seems to be from this Techcrunch article: https://techcrunch.com/2017/10/30/aws-continues-to-rule-the-.... It also has another graph showing the growth of Azure and Google being much higher than AWS. AWS has a head-start, but others are driving pricing down. Yay competition!
With 30-35% of the market (if that graph/article is to be believed), it's not even really fair to say AWS has a majority (majority being usually used for >50%).
The graph I posted shows Azure and Google growth being much higher as well. Think of it like this though: if you have 100 pennies and your growth rate is 75% then next year you will have 175 pennies. If you have 700 pennies and your growth rate is 35% then next year you'll have 945 pennies. Amazon offers a stronger product and just isn't going to "lose" market share at any point soon. I'm surprised IBM is even on there - I'd guess 90% of their cloud revenue is current customers that they converted over.
IBM acquired Softlayer, because otherwise their "cloud" offerings were basically marketing wank. Softlayer offered dedicated hardware, which a few years ago might have been appealing because of compliancy issues or lack of beefy machines on other cloud providers. In classical fashion, IBM snoozed and the competition has caught up (<insert IBM being morons rant here>). Great post if you want more detail: https://thehftguy.com/2018/01/15/the-inevitable-demise-of-ib...
https://imgur.com/a/TA5zg