Despite how halving increases the price of bitcoin to make it more profitable to investors, I'm wondering if it will not lead to devaluing of the currency in every four years?
Devaluation of currencies will not happen due to halving and its effect on Bitcoin. What will happen is a raised valuation of the coin, and the currency that will be most affected is the USD which will also not fall in value as people might seem but will have an adjustment against Bitcoin due to the appreciated value. This is not a currency devaluation but an asset increasing in its own value.
Will the effect of these not be inflation of bitcoin in every four years? I'm quit new in bitcoin, and I might be wrong, but I think that as halving continues to occur, bitcoin value might start to diminish gradually. And will it not negatively affect the purchasing power of bitcoin, in making payments for goods and services? I stand to be corrected.
You are mixing things together, Bitcoin halving is a tradition that will always happen and people tend to invest more money in the coin due to that, which in turn leads to its appreciation in price/value.
This will always not have any negative effect on Bitcoin itself but enrich the investors to further help fight inflation in fiats and have more power over their purchases.