I think the problem is the direction of investment from the sector. Investment in fake money that no-one really understands or can control (like toxic debts) is surely not as 'real' as investing in, for example, a high-tech manufacturing plant that makes real things that won't suddenly evaporate overnight when a bubble of fantasy and speculation explodes.
Whether it is possible or practical to direct or encourage the financial sector to invest in such a way I don't know. Market-fetishist dogma says no and perhaps that is true, but I don't think the idea is to smash the sector, as for it to function in a better way overall. We have discussed before that TfL is an organisation that works pretty well on the whole for a collective rather than a private interest, and there are doubtless other examples to suggest that it may be possible to run things more rationally than the pure market permits.