You are likely to have to trust them eventually. SPIC insurance is $500,000. If you have more than that and it turns out instead of buying the investments you think they were a ponzi scheme that sent the money to the owners when it is discovered you get up to $500,000 of your money back, while the rest is your loss. You really should have more than that by age 40 if you want a comfortable retirement (that is todays dollars, if you are 18 now when you hit 40 inflation will have made the number bigger, while if you are 80 the number when you were 40 would have been lower)
If you use a separate broker for each $500k then you only have to worry about multiple brokers catastrophically failing at the same time. And there are multiple types of account with each type having a separate $500k limit.
I'd rather not have to trust a non-profit insurance company to keep a very small portion of my funds safe. This stuff should be in-code and immutable by any one individual or corporation.
