Letter: National Debt Arithmetics

I am somewhat confused about the arithmetics being thrown around about raising the death limit. Be not mistaken, the trend of our deficit spending is a real problem that needs to be reined in. Anyway, both parties have contributed to our deficit spending. Ronald Reagan and Donald Trump have contributed with large tax breaks for the wealthy (44% of Americans do not pay federal income taxes). The Democrats contribute by legislating to develop our deteriorating infrastructure. Let's compare the two. If we spend $100M on fixing bridges, when it is spent, it is spent. When we lower taxes by $100M it is not over! That gift keeps giving and giving; years after year. Successful companies invest $Bs in the future. The internet is full of analyses showing the Trump tax breaks did not pay for them selves. What am I missing?