You probably mean deflation, right? In inflation the cost of goods and services are higher, because the currency is losing value.
Presently 6.25 BTC newly created with each block, about 1-2 BTC in fees. Mining has been paid for by increasing the BTC supply, for all of Bitcoin's history so far. Eventually that will have to change as the reward keeps halving. At some point there is no block reward and it's all fees. Will people pay enough in fees to sustain mining at a rate that's impossible for a large actor to 51%?
Ofc, if the mining is sufficiently large that it is impossible for anyone to collect enough power, then sure. But that is quite expensive proposition in general...
Maybe dilution is a better term? If all other factors could be held equal, then the real value of the ~6BTC reward for mining a block would, in effect, come from a tiny reduction in the real value of everyone else's BTC assets that would result from the supply of BTC having increased.
It creates an interesting situation. Right now, the cost of actually operating the BTC network is largely supported by every single person who owns BTC, proportionally to how much BTC they actually have. As the mining reward continues to taper off, that is going to shift toward the cost primarily being covered by transaction processing fees. That will change something fundamental about the economics of Bitcoin, although I'm not sure exactly how.