Excess protein inhibits calcium absorbtion. Lack of vitamin D inhibits calcium absorbtion. Milk is one of the best sources of calcium but --- soy milk actually has more calcium than regular milk per serving. However, calcium absorbtion is aided by Vitamin D, which is not naturally occuring in soy milk. However, your body produces vitamin D when you are out in the sun.
Contrary to popular belief, "oyster shell calcium" is actually NOT good for you. It can cause weird side effects when taken as a substitute for regular calcium.
Drink soy milk & go out into the sun more than you do when drinking regular milk and it won't make much difference, calcium-ly speaking.
Soy milk makes better milkshakes than regular milk because its thicker.
However, it is VERY high in sugar (depending on which kind you buy) so it can be bad for you in large quantities.
Also, soy milk is NOT good to cook with, generally. Depending on how you use it, it can either clot up or turn foul or scorch. I've used it to make cookies and some other simple things but don't use it in sauces or something similar.
Finally, you can never get TOO much calcium.
I'm sure you've heard of 'calcium deposits'... those are not caused by milk or what you eat or drink. They come from water & fluoride. If you are concerned about THOSE, get non-fluoride toothpaste.
And CHE, men SHOULD worry about their bones. It's rare for men to get osteoporosis, but it happens. It's also rare for women that haven't gone though menopause to have osteoporosis.... but it happens. I know someone very well who happens to have it and she is 21. She's had it for 4 years.