Time and varietal selection.
It looks like it may be one of the selections of palmatum that has very narrow lobes. Without seeing it close-up I can not even guess as to an ID. I am not the best on getting them to a cultivar but, it is not an exact science no matter who is doing it.

Other than the time and selection factors the only other thing is to plant your specimen in the correct light, in good soil, fertilize and water properly.

Patience is indeed a virtue when it comes to getting large Japanese maples; it is also a necessity.

How do I get mine to be like that? Wait 30 years?

At least :-)) That is a very mature tree. And any dissectum has the potential to achieve a similar size in time, at least with regards to spread. Ultimate height is dependent primarily on graft location.

There IS a market for large, specimen-sized JM's much like the one pictured. But be prepared to pay, and handsomely, for the time involved in achieving that mature size. As well as the added expenses involved in transporting and planting such a large tree. Most of us are forced to resort to exercising the patience hortus refers to :-) However, if well sited and given good care, many cultivars will grow more rapidly than one expects but it still takes many years to achieve that mature size.

If you live in the right zone, they grow very quickly. I would hazard a guess that in the right location, you can get one that size in under 15 years, assuming it is something like Inabe Shidari.

If you live anywhere near a Japanese Maple farm, go and look at the ones they have in fields, and ask them how old they are. You'll be suprised how large they can get in under 10 years if they're in ground.

Warren

Yes, age is probably 10-25 years based on specimens I have seen/photographed. Patience is a virtue I suppose.