If my time horizon is 1 year?
That's right: 2%
If my time horizon is x years?
-0.98^x + 1
15$ in transaction fees is nothing.
Also, props for the title, which mentions the money sent as if that were relevant for the transaction fee, as if the transaction were a percentage of that.
The digital gold narrative is newer and perhaps more powerful but I wouldn't call the transaction fees irrelevant.
The digital gold narrative comes from the blockstream|core|/r/bitcoin narrative that is desperate to keep the block size limit from expanding because their entire business plan is based around it. Anyone with common sense can see that a currency without fluid transactions is not very valuable, but with the constant and excessive censorship on /r/bitcoin and bitcoin talk some people have bought into thinking this somehow makes sense.
If you keep that much cash ... and simply put it in a long-term savings account, you'll earn just about enough to offset the actual inflation rate which is near zero.
But since you won't keep any huge amounts in cash, it's all moot, isn't it?