My understanding of church history is that upon arriving in Deseret, the church started several business enterprises. Individuals under church direction and without the benefit of tithing money started, church owned businesses such as, ZCMI, iron mining, and sugar and cotton industries among others. Income and losses from these activities formed the nucleus of the investment arm of the church.
To allege that all investment funds originally came from tithing is to either ignore history or be unaware of it.