benefits of tsp loans:
inflation. if gas costs $1 per gallon now and i hide $1 under my matress, does anybody think i will be able to buy more than 9/10's of a gallon later? this also speaks to living in the moment now vs. trusting someone else care for my living later. have you been to a nursing home lately? i would rather chew a juicy steak than be fed through a tube. besides, when i'm indigent that's what your tax dollars are for.
freedom: private brokerages (schwab in my case) offer etf's that replicate offerings in tsp, and more. in my brokerage and ira accounts i sling around allin trades of C/S/I funds equivalents commision free real time with no minimum required blocks of shares. ira replicates tax advantages of tsp. another roth ira defers tax advantages on the same trades for later adding diversity. a coverdale education ira also postpones taxes on gains for later and i was going to spend any gains in tsp for the same purpose anyways.
diversification: schwab offers a dozen and a half etf's that not only match us large cap, us small cap, corporate bonds, international large caps, and gov bonds. but also true small cap emerging markets; reit; 1-3, 3-10, and tips treasuries; and value, growth, and dividend indexes at no commision; plus the option of any marketable gold, silver, sin or green securities you can imagine at competitive market rates. why complain about sparse offerings and limited trades in the tsp then, unless you find value in complaining?
discipline: you can't splurge away your future in the tsp. bullcrap. you can easily, cheaply, and relatively quickly take out a tsp loan or hardship withdraw with penalty and buy any used minivan your heart desires, same as liquidating funds at any private brokerage. go ahead do it, everybody deserves a used minivan, not having one is a hardship you know. or don't do it if saving holds more value for you. who is pulling your purse strings?
last and best reason: because it's there. no explanation needed.
when i tally the whys and why nots of tsp loans, it always comes up why not.