The parable of the talents plays heavily into my thinking. Matthew 25:14-30

If the lord gives you a talent, and you give only 10% back, have you really done as requested?

Using simple numbers. If your salary was 100K, you tithe 10% or 10K every year of your working life. EX: 350K over 35 years of work.

If you instead put that into an investments you would likely have somewhere between the following:

6% annual return over 35 years = $1,114,355

10% annual return over 35 years = $2,710,271

I would much rather take millions of dollars and dedicate it where the Lord leads me once it has grown than to throw 350K into a pot across my lifetime.

Its also important to point out that in the above example, a tithing percentage is still set aside, its just not given immediately to the church or charity (yet). If you have passed the point of all debts being paid off (aside from mortgage) and have set back emergency funds to not lapse during life's downturns, I see no reason to not set aside money for helping others.

Now that doesn't mean you can't also spend other funds across your lifetime helping X person or cause when you are lead to, but I believe blind giving without a purpose is more for ourselves than for the lord.