It matters a lot, first because of the kind of God we serve. Do we serve a loving God who rescues the lost from death, or we serve a sadistic God who plans to torture people alive forever.
What if God actually wants to rescue the lost from death, but not everybody wants to be with Him for all eternity?
What if Jesus Christ's sacrifice provided the means for rescuing the lost from death, and it was 100% effective?
If death is conquered, then all are resurrected--with no possibility of physical death anymore. And if physical death is an impossibility, the only thing left for the "second death" is something that doesn't end.
[Rev 2:11] He that hath an ear, let him hear what the Spirit saith unto the churches; He that overcometh shall not be hurt of the second death.
so the second death "hurts" and it applies to people
[Rev 20:6] Blessed and holy [is] he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
[Rev 20:14] And death and hell were cast into the lake of fire. This is the second death.
definition of "second death", and it seems to apply to some group of people (based on 2:11) that are/were in a state of "death" or in the location of "hell" (Hades)
[Rev 21:8] But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
all those described herein "have their part" in the second death, which is further described with the word "brimstone", which seems to indicate that it isn't the concepts of death and hell that were cast into the lake of fire, but the inhabitants
So, if death is the penalty for sin, and if the second death "hurts", and people are resurrected from the first death to something more painful, presumably, doesn't that make God sadistic by your definition, even if it doesn't last for eternity?
On the other hand, if God is merciful and offers a way out of something that appears to be what things are like without God's organizing influence (all things consist in Him-Col 1:17 KJV), going so far as to describe the horrific nature of what can be avoided, but some don't take it, is that sadistic?