That's a lot of money to me but if I'd ever bought a lot of bitcoin before and I'm eligible to get that MN, I'll take it. $18 daily passive income is a nice amount for doing nothing and dash has a decent volume so it's a safe coin to invest.
Mining bitcoin and masternode, in my opinion the cost is almost the same. Masternode on certain coins requires more than 1 bitcoin while sometimes to build 1 mining rig does not cost 1 bitcoin. I think it depends on the investor, if you prefer bitcoin, then it's better to build the rig