So you are talking about whether it's best to invest money in buying bitcoin and holding it or go with the amount on buying ASIC machines for mining bitcoin right?
Let's take example that you invest your money for going to invest for full bitcoin so at this time you would need to spend $21400(at the time of writing this post as price fluctuate every second keeping volatility in mind) and there is no additional cost for it and you can story them in non custodial wallets or hardware wallets for long term.Now suppose the price is above $30k in span of one month so you make $8600 in profits at the time if you want to sell your coins but it could have been opposite also but depends if you prefer to hold long term then profits will be there.
Now speaking of Mining then you need to have ASIC machines and setup to run them with all time electric connection and join the mining pool as solo miners don't have the high probability of finding a block.You also need to look for the electricity cost, maintaince cost and cooling pads not to overheat it or if you live in high temperature region like some parts of Asia.
You see there is lot of work with mining but once you start getting rewards according to your contribution you can keep the bitcoin and it will accelerate your profit margins with bags filling with bitcoin but you also need to spend on the maintenance, electricity while doing the job so be sure about it.