Well, 100K in profit (depending on the business structure) may end up costing more than 25% in taxes once federal, state and any self employment taxes get figured in.

If they are in need of a piece of equiment that they may be planning on purchasing in the near future anyhow, it may be a good time to do it before year end.

Everyones tax situation is different, whether it make sense to buy this asset is something the accountant should be able to explain based on their particular situation.  Depreciation doesnt have to be taken all at once, there are several different planning opportunities that are available.