He has a complicated web of half a dozen companies, going back several years, whose main sources of revenue seem to be private investment and subsidies given by the Australian government to R&D companies.  To justify the latter, he used deals between his own companies and his family trust fund.  At one point he claimed that one of his entities bought private software from another of his entities, for tens of millions of dollars -- allegedly paid with bitcoin.  And he tried to use that deal to get more R&D subsidy money.

So, for several years he has had two possible motives to pretend to be Satoshi: to dupe investors, and to explain to the Australian government how he could have so much bitcoin.