That particular tree is pretty quick (as aloe trees go anyway) but a young seedling probably wouldn't get that big in your lifetime.
It grows very differently depending on how much water you give it (total opportunist) and what kind of soil it's in. Obviously it would be seriously limited (and probably quite frustrated) after many years in a container.
There's another aloe called "Hercules" (a hybrid between two large trees) which grows humongous as well, but it has a gnarly bark and a bit more attitude. You'd be surprised at the diversity of tree aloes, something which is generally best appreciated in the flowers. Here's one of the so-called "single stemmed" tree aloes (no branching just one big fat rosette on a stem that grows to about 15 feet tall with advanced age).
And the flowers have some very rich colors when they open.
The tree aloes tend to put out these spectacular flowers once a year, after they get to a certain age. Here are a few tree aloe flowers from this winter... a couple of these are hybrids that I grew from seed.
